The infantry of the Western Allied Forces, now with an armor penetration rate approaching one hundred percent, were tasked with providing cover, with the supporting troops being heavily armored heavy infantry.
Facing such a ferocious assault, even though Yumenguan was well-prepared, the pressure was immense.
Nan Jiyun, overseeing the battle from the highest tower, made a decisive move, waving his seventh command flag.
Instantly, the sound of war drums shook the heavens.
"The Marshal commands: Unleash the Skyfire!"
As the order spread, over a hundred small catapults, waiting at the very rear of the city walls, finally sprang into action.
Each catapult was equipped with spherical clay pots, weighing twenty catties. Each pot had an opening connected to a long fuse that could be lit, containing petroleum.
However, within the clay pots, near the connection to the fuse, a small wooden sphere filled with gunpowder was embedded. The sphere was covered in a thin layer of mud, akin to placing a box of explosives inside the clay pot. The gunpowder, upon landing, was more resistant to impact due to the wooden exterior and the predominantly earthy terrain outside the western territories.
After the soldiers lit the fuses, all the small catapults sprang to life, hurling the clay pots into the distance.
"Whoosh! Whoosh!"
The soldiers of the Western Allied Forces, taking advantage of the night's cover, only saw streaks of fire flying through the air. As they wondered what it was, the "fire streaks" were already upon them.
"Boom!"
Some of the clay pots exploded before they even hit the ground, spewing flames that seemed like heavenly fire descending, burning vast areas!
The remaining clay pots, even if they didn't explode upon landing, quickly ignited the flowing petroleum on the ground.
In the blink of an eye, the area a hundred to two hundred zhang outside the city transformed into a sea of flames, terrifying the Western Allied Forces and temporarily halting the enemy's advance!
"Why can this land, composed entirely of soil, ignite?!"
Due to the intense heat, the vanguard of the Guishuang Dynasty forces finally felt fear.
The firelight also illuminated the direction for the defenders on the city walls, and another volley of tens of thousands of crossbow bolts pierced through armor, harvesting the chaotic enemy troops on the ground.
"Marshal, the enemy's defense and alertness far exceed our estimations. They can even ignite the sand!" a messenger reported urgently.
Attila roared, "Fighting in sandy terrain, you fools!"
Mars bellowed, "Do I need to teach you how to extinguish fires with mud and sand on the spot?"
The messenger suddenly understood and hurried off to relay the message.
The firelight reflected Mars's extremely grim expression. The sudden turn of events, requiring him to explain such basic common sense, indicated the army's poor quality, even though these were only slave soldiers.
However, he also knew that if they didn't press the attack tonight, forcing the Da Gan soldiers to remain on high alert and constantly vigilant, their chances of winning would diminish as reinforcements arrived and a decisive battle ensued. Even though the area around Yumenguan was ideal for cavalry, they had a secure supply line.
But Liang Xiao's strategy in the flatlands of Jiangnan had annihilated the once invincible Heavenly Sun cavalry...
The offensive of the Western Allied Forces did not slow down due to the new Da Gan Skyfire; instead, it intensified.
The slave soldiers quickly filled the fires with sand, disregarding casualties, and continued to charge through the Da Gan Skyfire.
The two sides fought fiercely for over two quarters of an hour, with a total of over five thousand casualties.
Forty Shenwu cannons were mounted on Yumenguan, their roars continuous.
However, these Shenwu cannons could not be loaded with explosive shells, and while their siege capabilities were sufficient, their lethality was limited. Thus, their deterrent effect in large-scale battles was restricted.
The Western Allied Forces' replica Huihui cannons, after a prolonged push, had, under the cover of heavy infantry, approached their firing range. Hundreds of stone projectiles bombarded the city walls. A small number of these projectiles bypassed the walls, killing and wounding dozens of Da Gan soldiers on the ramparts.
The Da Gan soldiers did not retreat, but the cover of darkness prevented the Yumenguan defenders from accurately locating all the replica Huihui cannons.
Fortunately, the Shenwu cannons had an advantage in height, distance, and initiative over the Huihui cannons on the wall. Experienced artillerymen, observing the landing and rolling direction of the distant Huihui cannons, quickly pinpointed their locations and adjusted their aim.
"Boom!"
A large number of replica Huihui cannons were smashed by the Shenwu cannons and Huihui cannons on the wall, followed by volleys of arrows, causing immense casualties.
The cavalry units harassing the flanks of Yumenguan were also subjected to a combined barrage from Shenbi bows and longbows, with countless riders being shot off their mounts.
The commanders of the Western Allied Forces, directing from a highland five li away, relayed information through a constant stream of messengers to quickly grasp the frontline situation.
"Our Huihui cannons failed to penetrate the enemy's city walls and over a hundred were destroyed. More than three thousand of our cavalry operating outside the city were shot dead."
Upon receiving the urgent report, their expressions turned grim.
Attila, gazing at the moon peeking through the clouds, sighed, "Retreat."
The Western Allied Forces, which had surged forward like a tide, receded like one, leaving behind over twenty thousand corpses.
"The Da Gan Skyfire is indeed formidable. It's no wonder the Izumo Kingdom suffered such heavy losses," Mars said with a dejected look.
No one questioned Attila's strategy of a swift assault, as the slave soldiers of the Guishuang Dynasty were considered expendable in their eyes.
However, Yumenguan stood like an impregnable fortress, its defenses far exceeding their expectations. Even with the worst-case scenario planned, they had underestimated it.
"Failure was within expectations, but we must not allow the enemy to gain an advantage by resting. We must frequently feign attacks to create opportunities for our army to harass areas east of Yumenguan," Attila said, pointing to the map as he analyzed. His eyes sharpened, "The reason the Da Gan army has hesitated to sortie out of the pass is not cowardice. They are likely deliberately waiting for us to establish supply lines, lulling us into reinforcing our troops."
Everyone's expression changed. "You mean they are luring us to concentrate outside Yumenguan for a decisive battle?"
Attila clenched his fist and gritted his teeth, "You have all experienced the defensive capabilities of Yumenguan. We must continue our harassment while being prepared to retreat at any moment."
Mars finally slammed the table, "Attila! The swift assault was your proposal, and the unsparing establishment of supply lines was also your proposal. Do you truly intend to treat our Heavenly Sun cavalry like monkeys?"
Attila retorted coldly, "I only spoke of retreating, not of disbanding. If necessary, our army must lure the enemy deep into our territory, retaliate against Liang Xiao, and annihilate them! Regardless, this decisive battle will determine the destiny of Da Gan and our nations. We can only win, not lose!"
Everyone suddenly understood. Mars's expression softened slightly, and he apologized as he left his seat.
Nan Jiyun, after tallying the battle losses, discovered that the defending forces had suffered over a thousand casualties, and his expression was grim. This was a defensive battle, yet it showed the enemy's ferocity. If the Da Gan army had sallied out for battle in the past, even if they had achieved a great victory, they could not have annihilated the enemy, nor could they have pursued them all the way to the Guishuang Dynasty. They might even have suffered a setback. Now, he finally understood the significance of Liang Xiao's order for Yumenguan to hold its ground for the time being.
In the following days, Yumenguan was frequently harassed by the Western Allied Forces, but it remained unyielding, strictly defending and preventing the enemy cavalry from easily crossing the pass.
"Marshal, the Emperor has arrived!"
Several days later, the excited shouts of the generals dispelled Nan Jiyun's gloom over the casualties, and he rushed out of the pass.
Liang Xiao had finally arrived inside Yumenguan to take command.