The southeastern valley of the Fen River covered the counties of Jiang, Wenxi, Quwo, and Yicheng. The terrain consisted mainly of low hills and river-formed alluvial plains, favorable for cavalry flanking maneuvers. The Mongol forces occupied multiple fortified cities within the valley, fighting with城-based tactics while possessing overwhelmingly superior elite cavalry. From any perspective, the Mongols held the greater advantage in this battle.
Han Qian did not wish for the two armies to continue their standoff on the northern slopes of Mount Wangwu, while Wusu Dashi was also eager to engage in a decisive battle in the southeastern Fen River valley.
Every family has its own difficulties to recite. Han Qian worried that relations between Daliang and Shu-Chu could undergo subtle changes at any moment, while Wusu Dashi also had pressing reasons to seek a decisive engagement.
Beyond the fact that organizing a major battle now was more advantageous for the Mongol forces, Wusu Dashi also feared that if the Liang army established solid strongholds in the northern foothills of Mount Wangwu near the northern pass of Zhiguan Gorge, even a small Liang force could tie down large numbers of his troops. It would directly threaten agricultural production in the Fen River valley plains, which accounted for one-quarter of the population and farmland of the former Hedong commandery. This meant that this winter, the Mongol army absolutely could not simply defend the few fortified cities like Jiang County and Quwo.
As the core passage connecting Taiyuan with Guanzhong, the Fen River valley’s strategic importance was clear not only to someone of Wusu Dashi’s stature, but even to mid and lower-level officers. If the Liang army thrust like a sharp blade toward the Fen River’s banks and time dragged on, their subsequent control over Guanzhong would inevitably be severely weakened.
Since the southern invasion, military affairs had gone extremely well, but after Han Qian took control of Heluo, Mongol strategic intentions had repeatedly been frustrated. Liang Shixiong’s elite Weibo troops and Tian Weiye’s elite Luzhou forces had been completely annihilated in succession, greatly affecting the morale of the Southern Court’s officers and men. This also led the Northern Court to become increasingly presumptuous in voicing opinions and meddling in Southern Court affairs.
Wusu Dashi urgently needed a new victory to reestablish his prestige.
To lure the Liang army out from the northern section of Zhiguan Gorge’s narrow valley for a decisive battle, in early October Wusu Dashi even sent envoys into Yuanqu City to meet with Wen Bo, agreeing that the Mongol army would withdraw from the northern slopes of Mount Wangwu, giving the Liang army space to deploy their forces. The two armies would fight to the death in the open terrain southwest of Jiang County.
Subsequently, the Mongol forces advancing on the northern slopes of Mount Wangwu did indeed contract northward, but Wen Bo would not naively believe that Wusu Dashi truly possessed the “magnanimity” of Duke Xiang of Song, that he would actually let them comfortably move all their forces out from the deep canyons and valleys of Mount Wangwu before launching an attack.
In the early phase, Chen Yuanchen led infiltration forces in extensive preparatory work, conducting thorough and detailed reconnaissance of the terrain on the northern slopes of Mount Wangwu and around Jiang County. Besides marking almost all of the hundreds of large and small mountain ridges and peaks, slopes and dry gullies, streams and river channels, as well as wild paths and mountain roads on the latest operational maps, they also dispatched two to three liaison guides to each of the more than three hundred main battle and reserve battalions participating in the campaign.
Chen Yuanchen did not directly command troops in battle but instead entered the vanguard camp’s military intelligence staff department to directly assist Wen Bo in military planning.
When the Mongol forces contracted northward, Wen Bo commanded his troops to exit the pass and then spread out toward the mountainous terrain on both flanks through the relatively gentle slopes and valleys of the northern foothills, overcoming difficulties.
If they had truly advanced directly northward along the Jiang-Yuanqu post road as the Mongols anticipated, before reaching south of Jiang County city, they would inevitably have been fiercely counterattacked by Mongol forces. With large numbers of their troops congested on the narrow Jiang-Yuanqu post road, unable to deploy, and their flanks subjected to fierce cavalry attacks, they could easily trigger a complete collapse.
Wusu Dashi could not possibly wait until the Liang army’s main force had comfortably deployed before engaging in battle. Seeing his stratagem had failed to sell, and large numbers of Liang troops flowing like a blue-black flood through the relatively gentle slopes and valleys, spreading toward the mountainous terrain on both flanks of Mount Wangwu’s northern slopes, he immediately ordered the vanguard forces to turn around and attack southward along the Jiang-Yuanqu post road.
Through his brass telescope, standing atop the southern tower of Jiang County, watching the Liang army pour out from the pass like a flood, the shadow in Xiao Yiqing’s heart grew heavier.
Although their reconnaissance had discovered that the reinforcements Han Qian had transferred northward from Yingxi and other areas consisted mostly of reserve soldiers whose combat effectiveness was not particularly strong—indicating that Liang’s military accumulation over these years was not sufficiently robust, and as they were defending a region surrounded by potential enemies on all sides, it was difficult to commit all their elite forces entirely to one battlefield—watching the flood-like Liang army pouring out, Xiao Yiqing could sense that the Liang court and ministers’ determination and urgency to engage in battle was even stronger than their own, inevitably producing a hint of self-doubt.
Generally speaking, the most brilliant strategies should strive as much as possible to “make the enemy do what they do not wish.”
Simply put, if the enemy fears battle and avoids battle, one should use every means possible to force them to respond and fight; but if the enemy is eager to fight, one should conversely delay the timing and wear down the enemy’s patience, waiting for circumstances to shift in a more favorable direction.
In the current situation, both sides were eager to engage in decisive battle.
Comparatively speaking, they held the advantage in troop numbers, but currently it appeared that launching a decisive battle from Zhiguan Gorge was a plan the Liang army had long been plotting. Besides being slightly inferior in troop numbers, they must have made more thorough preparations in the early stages than they had.
The vanguard forces of both armies soon made contact on the Jiang-Yuanqu post road and the open terrain on both flanks. Together the two sides’ forces numbered over twenty thousand men. Watching from afar atop Jiang County’s city walls, one saw surging floods, with sounds of slaughter, wind, neighing horses carrying over eleven or twelve li, stirring the heart.
At this time, the battle had only just begun. As various units deployed their forces on both flanks of Jiang County, messenger cavalry could still move quickly and orderly between the units’ encampments. Wusu Dashi could still control the battle’s evolution and development, but as the fighting entered a more intense phase, the forces of both sides would unavoidably become interlocked like dog’s teeth. At that point, they would have to rely more on the command and coordination of front-line officers.
Xiao Yiqing clearly knew the Mongol army was at a disadvantage in this regard. They needed to maintain their formations’ discipline as much as possible.
When necessary, they could even use elite cavalry to rapidly strike Liang formations without regard to casualties, scattering them so that subsequent, more disciplined infantry armor formations could advance forward. They needed to avoid engaging in interlocked, chaotic battles with the Liang army as much as possible.
Of course, they were fighting with城-based support, so they still held absolute superiority in controlling the entire battlefield.
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When enemy forces counterattacked, Wen Bo immediately ordered the forward units to contract southward along the Jiang-Yuanqu post road, and ordered the forces that had already spread to the mountainous flanks to assemble in place, utilizing light battle wagons as much as possible to stabilize their formations. Along the Jiang-Yuanqu post road and the mountainous terrain on both flanks, they formed a pocket formation to strike at enemy forces advancing southward along the Jiang-Yuanqu post road.
When enemy forces contracted northward, the forward units continued advancing northward along the Jiang-Yuanqu post road while continuously expanding into the slopes and valleys on both flanks.
Over three days, the two armies fought more than thirty engagements large and small along the Jiang-Yuanqu post road, with each side suffering several thousand casualties. Relatively speaking, suffering too greatly from unfavorable terrain in the early phase, the Liang army’s losses were slightly higher, but they had also successfully secured a sufficiently large deployment area in the southern Jiang County region.
Excluding reserve forces, six infantry combat brigades, three cavalry brigades, and six reserve brigades fully entered the southern Jiang County area.
During these three days, Han Qian remained at Red Stone Fortress deep in the northern section of Zhiguan Gorge canyon, silently monitoring the battle’s progress. He did not go to the front lines to supervise the battle, nor did he send anyone to convey a single word or deliver a written edict to Wen Bo.
The more than forty thousand reserve troops had also been moved out from Zhiguan Gorge’s northern pass to camp, meaning the conditions for final comprehensive battle had matured.
For Wen Bo and Guo Que, who had been ordered by Han Qian to serve as chief military advisor since the northern campaign from Zhiguan Gorge began, this moment felt like a massive boulder pressing on their hearts.
This battle would fundamentally determine the direction of the northern theater. Though Wen Bo had experienced many life-and-death battles in his lifetime, at such moments he felt not the slightest ease, deeply feeling the enormous pressure on his shoulders.
After Wen Bo and Guo Que, accompanied by a group of staff officers, inspected the forward fortifications and returned to the central camp, they saw from afar an additional contingent of Security Brigade soldiers beside his great tent. Looking toward Huo Li, who came to the front of the camp to greet them, he asked, “Has His Majesty arrived?”
“His Majesty is inside the great tent with Noble Consort Shu and Lady Xi,” Huo Li said.
Wen Bo’s mood at this moment was complex. He felt the weight of responsibility, yet did not wish for Han Qian to directly interfere with his frontline command authority.
In his view, even if Han Qian could restrain himself from saying anything, Han Qian’s arrival at the vanguard camp would transmit subtle signals to the officers below, thereby interfering with his battlefield decisions.
Wen Yuan coughed lightly, reminding his uncle Wen Bo that regardless of the circumstances, he should not display a displeased expression.
Wen Bo suddenly realized that throughout the entire army, not a single person could match His Majesty in the use of troops. Could there truly be some subtle matter on the battlefield that he had overlooked, forcing His Majesty to break his word and arrive early?
With this thought, Wen Bo leaped down from his warhorse and, together with Guo Que, Wen Yuan, Chen Yuanchen and others, strode rapidly toward the great tent.
Accompanied by Feng Liao, Gu Qian, Han Yuanqi, Yin Peng and others, Han Qian sat in the great tent with Zhao Ting’er and Xi Ren, speaking with several mid and lower-level staff officers on duty around the long military conference table. Seeing Wen Bo and his group announced and entering, he stood up with a smile and said, “I’ve broken my word. Seeing me sitting here, you must be quite displeased, aren’t you?”
“This subordinate would not dare,” Wen Bo saluted. “That Your Majesty has hastened here must mean Wen Bo’s considerations had inadequacies that caused Your Majesty worry.”
“You’ve done very well; there are no inadequate aspects,” Han Qian gestured for Wen Bo and the others to sit and talk, saying, “However, if there is no strong wind tonight, Ting’er predicts there is a high probability of heavy fog on the northern slopes of Mount Wangwu tomorrow morning at dawn. I felt I should remind you of this point…”
“May I ask Noble Consort Shu, what exactly does ‘high probability’ mean in terms of certainty?” Wen Bo couldn’t help but stare at Zhao Ting’er and ask.
The Fen River valley’s autumn and winter weather was cold and damp, prone to heavy fog—this was something Wen Bo had known long ago. But the problem was he could not accurately predict under what conditions heavy fog would actually form. Therefore, foggy weather was a neutral factor for both armies’ forces that required vigilance but was difficult to exploit.
If they could more precisely predict fog formation, they would be able to completely seize the initiative in large-scale military operations—and in foggy weather, if they could lure the enemy’s main force out from their fortifications to fight while having advance psychological and comprehensive preparation, they could more fully leverage the advantages they had formed in their command system.
Wen Bo’s original plan was to rest for two days, then push their military edge deeper into Jiang County territory, approaching the enemy’s forward line to conduct attritional warfare, testing or consuming the enemy forces’ will to fight.
This was the most conservative and most reliable method of warfare.
But if they could confirm that heavy fog would definitely arise tomorrow morning at dawn, this would be absolutely critical.
He could even directly adjust the established operational plan, possibly deploying the reserve brigades with much weaker combat effectiveness to the central line that very afternoon, advancing along the Jiang-Yuanqu post road toward the enemy’s forward line to attract the enemy’s elite main force to come out to this line.
Meanwhile, Daliang’s truly elite combat brigades and cavalry brigades would be deployed to both flanks under cover of night.
When heavy fog arose tomorrow morning at dawn, the elite combat units would penetrate directly from the flanks deep into enemy territory, directly attacking the enemy camps on both flanks of Jiang County city, drawing the eighty to ninety thousand enemy main force troops assembled in Jiang County territory directly into a chaotic decisive battlefield for merciless strikes and annihilation, using this single battle to crush the Mongol army so thoroughly they could never recover.
All units had long established staff systems, and the northern expedition forces had established a forward staff department led by Guo Que even before the war to assist Wen Bo in handling various complex military affairs. Contingency plans for various situations had been drafted long ago.
The question was: Wen Bo needed to confirm exactly how high this “high probability” actually was.
If it only slightly exceeded fifty-fifty odds, deploying the reserve brigades with weaker combat effectiveness concentrated along the central line of the Jiang-Yuanqu post road, but then no fog arose tomorrow, the enemy forces would very likely seize this weak point to fiercely counterattack, causing the battle situation to turn thoroughly unfavorable for them.
“For three consecutive days, measured atmospheric moisture content has been steadily increasing, reaching saturation by midday. The key still depends on whether wind arises at night. South wind poses no great problem, but if dry, cold north wind arises at night, scattering the moisture, fog will be difficult to form. The probability of fog formation also requires more accurate prediction based on the night wind’s strength. With no wind or gentle breeze, heavy fog will definitely arise tomorrow morning at dawn. If rustling-leaf wind arises at night, based on the Engineering Institute’s current experimental data, fog probability drops to eighty percent. If condition-humming wind arises, fog probability drops to sixty percent. Above swaying-branch wind strength, moisture will most likely dissipate…” Zhao Ting’er said.
In the previous dynasty, Li Chunfeng had authored works conducting preliminary research on wind as a weather phenomenon, dividing wind force magnitude into ten grades: “no wind, gentle breeze, rustling-leaf wind, condition-humming wind, swaying branches, falling leaves, breaking small branches, breaking large branches, breaking trees, flying sand and stones, and uprooting large trees.”
The Engineering Institute currently had more precise measurement methods, but wind force classification still followed the old conventions.
The Engineering Institute’s research on weather prediction had only just begun and was far from precise. They had achieved some presentable results only with fog formation conditions, which were relatively simple, but had not yet formed a comprehensive weather prediction system. Neither the comprehensive schools in Liyang and Luoyang, nor the various regional forces’ military intelligence staff departments had yet promoted this…
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Rotating units into frontline combat to effectively reduce soldiers’ physical exhaustion, distribute casualties, and provide timely and effective personnel replenishment was a routine tactical arrangement.
After the Liang army exchanged unit designations, that afternoon they deployed three reserve brigades to replace three main infantry combat brigades on the forward line, then subsequently sent two additional reserve brigades to the forward line. It was difficult for the Mongol army to discern anything unusual in this.
And Wusu Dashi, not wishing to see Mongol forces on the forward line pressed back again by the Liang army, not wishing to see the Liang army more comfortably deploy their forces in the open terrain of southern Jiang County or even push their military edge to beneath Jiang County city, only correspondingly mobilized troops to strengthen the force deployment on the forward line deployed along both flanks of the Jiang-Yuanqu post road.
After nightfall, through dense torches, seeing signs of large Liang forces crossing the mountainous terrain on both flanks to outflank and attack the flanks of his forward line, Wusu Dashi simultaneously reinforced troops behind the simple protective fortifications on both flanks of the forward line. Unknowingly, both sides had accumulated large numbers of troops on the forward line and both flanks.
At midnight, the weather was still with no wind. Clusters of fog vapor first rose from the Fen River, then spread toward both banks.
Since the Luoyang naval forces controlled the Fen River channel, except for small numbers of scout cavalry, Mongol camps were all quite distant from the riverbank.
The Fen River valley commonly had heavy fog in autumn and winter. Scout cavalry did not realize there was anything unusual or worthy of vigilance about fog vapor spreading from the river toward both banks after midnight.
They only positioned themselves closer to the riverbank than usual, watching that Liang warships made no unusual moves. They did not even think there was any direct connection between the night battle the two armies had initiated on the forward line forty li away and the fog vapor rising along the river at this moment.
Seeing several Kongming lanterns rise above the Fen River from afar, confirming that heavy fog had first arisen along the river, at Wen Bo’s command, Cao Ba and Lu Ze mounted their warhorses.
Their combat mission was to each lead three thousand elite troops, crossing more than twenty li of valley slopes and small paths on both flanks before dawn, taking the lead in launching surprise attacks on enemy forces on both flanks of the forward line, tearing open breaches. They would then cover the forty thousand main infantry combat brigade elite forces that had already entered the flanks’ reserve attack positions, penetrating directly toward enemy depth along the open terrain on both flanks of Jiang County city, launching surprise attacks on the Mongol army’s two cavalry main camps before the fog dispersed.
Both sides had assembled too many troops in the southeastern Fen River valley, and while Jiang County’s city walls were solid, the city was small and could not accommodate so many troops. Moreover, Wusu Dashi absolutely did not intend to fight a defensive siege battle while watching the Liang army establish camps south of Jiang County.
Excluding Wusu Dashi’s escort forces, the ninety thousand Mongol main forces were primarily camped on both flanks of Jiang County and on the forward line blocking the Liang army’s continued northward advance.
An hour later, Wusu Dashi and Xiao Yiqing noticed the fog vapor in Jiang County city becoming heavier with moisture, but they did not raise sufficient vigilance. After all, heavy fog weather was an equally disadvantageous neutral factor for both armies. While he ordered all units to strengthen vigilance, he also assumed the Liang army would become more cautious facing the sudden weather change.
The night battle hastily initiated on the forward line ceased as the Liang army contracted, which also seemed to match their predictions.
Had it not been for his consistent caution, Wusu Dashi would have wanted to return to his sleeping quarters to rest.
Wusu Dashi and Xiao Yiqing perceived something unusual when officers on the forward line’s flanks detected that the Liang army’s advance through the slopes and valleys in the dense fog had not been interrupted by the heavy fog. But by this time, dawn was already breaking dimly. The moisture-heavy fog vapor was condensing into water droplets on the window paper. Opening the room door, even the scenery in the small two-zhang courtyard could not be seen clearly at a glance.
After the heavy fog arose, distant torches were obscured and could not be seen. Scout cavalry on both flanks judged through disturbances at the edge of areas controlled by both armies that the Liang army had been continuously assembling on the southern flanks of the forward line, and on a massive scale far exceeding their expectations.
Xiao Yiqing stood up in alarm. The Liang army had predicted today’s heavy fog and had long planned and deployed to launch surprise attacks from both flanks in the fog?
“All messenger escorts move out immediately, relay orders for all forward line and flank camps’ soldiers to immediately form defensive formations!” Wusu Dashi shouted loudly.
The camps on the forward line were far too crude—simple palisade walls or thin rammed earth protective walls plus shallow ditches and narrow moats could be easily breached without any war machinery.
And in the heavy fog, lighting bonfires could not illuminate far.
Although they had means to maintain contact and identify directions in heavy fog, the problem was the Liang army had come prepared and had made more thorough preparations in these areas than they had. Meanwhile, soldiers on their forward line might have already dispersed into tents to rest. How could they possibly make adequate combat preparations when hastily assembled?
The only response to guard against Liang surprise attacks in heavy fog was for all units’ soldiers to gather together as much as possible, forming circular defensive formations to hold their positions, doing everything possible to avoid falling into chaos.
To prevent Liang scouts who had already infiltrated from intercepting messenger escort cavalry, Wusu Dashi simultaneously ordered soldiers atop the city tower to beat war drums and blow horns with maximum force as warning.
Xiao Yiqing followed Wusu Dashi up to the southern city tower. All he could see was fog vast and boundless between heaven and earth, with scenery beyond ten zhang completely shrouded in heavy fog. His heart sank like a stone to the bottom of a well. Soon news came that the Liang army had launched surprise attacks from both flanks, making their expressions even more grim.
“The Tiger Vanguard Battalion on the right flank has been broken by the Liang army. Casualties on both sides unknown. Camp tents set ablaze by Liang forces. Soldiers scattered in all directions. Liang forces appear to be heading toward Elm Gully…”
“The Armored Vanguard Battalion and Crooked Mountain Battalion on the left flank broken by Liang army. Liang forces appear to be heading toward Field Hollow Bay…”
One piece of unfortunate news after another arrived, striking their ears like thunder.
“The Liang army is heading for the cavalry main camps!” Xiao Yiqing said in alarm.
Although the intelligence transmitted back was chaotic, he had no difficulty analyzing the intentions of the Liang forces that had launched surprise attacks from both flanks.
The terrain of southern Jiang County still consisted primarily of shallow low hills. The forward line and both flanks were mainly defended by Yan-Yun Han Chinese troops and submitted army infantry. The cavalry main camps were deployed on the flanks and rear of Jiang County city, with the hope of pushing the Liang army step by step to Jiang County city, then using cavalry to attack their flanks from the open valleys.
Unable to deploy in heavy fog weather, tens of thousands of cavalry were now huddled in several connected camps on both flanks.
They had not considered that Liang infantry and cavalry would dare to penetrate so deeply in the early phase. Moreover, cavalry was not meant for defense—the connected camps’ defensive facilities were extremely crude. Suddenly encountering enemy surprise attacks, unable to form battle formations, and unable to conduct flanking maneuvers in heavy fog weather, heaven knew what chaos would result when the Liang army burst through in surprise attack.
“Quickly order Zhehe and Minshan to have their units abandon camp and disperse toward Quwo, Wenxi, and Yicheng. They must not engage the enemy in hard battle!” Wusu Dashi ordered.
Cavalry came and went like the wind. Abandoning the main camps would cause no losses. After the fog dispersed, they could easily reassemble. Otherwise, engaging in chaotic battle with a prepared enemy in heavy fog—who knew what slaughter they would suffer!
Watching several escort cavalry exit the city gate, spurring their horses deep into the heavy fog to rush toward the cavalry main camps with orders, Xiao Yiqing’s heart remained troubled. If this surprise attack was something the Liang army had long planned, it meant their naval forces had most likely already landed and formed defensive formations on the flanks of the cavalry main camps to intercept.
In such heavy fog weather, cavalry would find it very difficult to organize any proper attack. Once intercepted and thrown into chaos, the vast majority of cavalry deviating from the main roads would lose their ability to identify directions. At that point, they could only fall into chaotic individual battles—the consequences would be catastrophic.
Yet besides sitting and waiting for the fog to disperse, they could do nothing more…