SCRIPT - The Mongol Conquest of Southern China (02/09/2018)

The Mongol Conquest of Southern China

This video will be about the Mongol conquest of Southern China and the Sòng Dynasty, a titanic effort that would last from the 1230s to 1279 and involve, directly or indirectly, all the states of East Asia and many beyond. In particular, this video seeks to place Mongol and Song actions within a larger strategic and regional context. 

 

Geography

Unlike the plains of Northern China, the hot, humid and hilly geography of Southern China is bad for effective cavalry operations. This was not purely to the Mongols’ disadvantage, however: it also prevented the Song from raising the cavalry necessary to mount a serious challenge in the North, which meant they were on permanent defense.

Geography also meant that riverine travel was by far the more efficient means of transportation in South China. The Song thus had to rely on the Yangtze River network as both their northern line of defense and a major communications highway, which deprived them of the advantage of interior lines. Any blockade of the Yangtze along the 1,650km front would split the Song in two. 

The Song’s Yangtze frontier could be divided into three distinct theaters of operations. Firstly, there was Sìchuān in the west, isolated from the rest of China through mountains and distance and mostly acted independently of the central government in Hángzhou.

In the center was the Hàn River Valley, whose north-south orientation into the Yangtze Basin made it a natural highway linking North to South China, and thus a gateway for the Song moving North, or the Mongols heading South. A series of Song fortresses guarded the riverbanks, most notably the twin cities of Xiāngyáng and Fánchéng at its northern end.

In the east, communications between inland China and Hangzhou inevitably passed through the lower Yangtze, making this wealthy region a key strategic point in the Song Dynasty. It was comprehensively defended and fortified, with a network of fortresses, walled villages and water obstacles from the formal boundary at the Huái all the way to the Yangtze, whose waters were patrolled by dedicated riverine fleets.

Taking a broader regional view, the Mongols by the 1230s possessed an Empire stretching from European Russia and Persia to the border with Korea, which also meant having to watch out for enemies as far-flung as Central Europe, Anatolia, Iraq and Northwestern India.

They also could not afford to ignore the extensive Song relationships with East, Southeast and South Asia: not only would the Song draw wealth and resources from them through trade, but there was also the potential that these countries would aid the Song in order to protect themselves.

Approaches to War

In attempting the conquest of Southern China, the Mongols would not just fight in terrain that they were not accustomed to, but also against a strategy and political system different to anything else they had fought before.

On a policy level, the Khans, needing to demonstrate success and secure plunder for followers, acted on the basis of perpetual war. In order to avoid overstretching the hundred-thousand men of the ‘core’ army, Mongol grand strategy hinged on the idea of ‘one war at a time’, exploiting the Empire’s central position to crush an enemy on one front before the others could react. Dealing such crushing blows, in turn, meant giving subordinates freedom to conduct wars of maneuver, with the Khan setting only the overarching objectives and timetable.

The Song, on the other hand, practiced a policy of ‘coexistence’: rather than getting into direct, costly and risky conflict with the militarily-superior nomads, the Song would pay them off and wait as the latent instability of steppe politics tore their rivals apart. Their grand strategy therefore focused on preparing the state to withstand long wars and dragging out conflicts beyond what the nomads could bear. This, in turn, led to a strategy focused not just on forts and the barrier of the Yangtze, but also on establishing a strong economy and centralized control as a means of ensuring political stability.

The question of securing naval control would loom large for both sides. Naval control not only determined whether the Yangtze could be penetrated in its middle and lower reaches, it also impacted the security of riverine, coastal and canal communications, contact with other states, and the viability of overseas trade.

For the Mongols in particular, naval questions also tied into the broader internal debate over their future development. Bureaucracy and settled government were required to fund and maintain a navy, but such reforms exposed the Khan to the wrath of the traditionalists.

Internal divisions also ate at Song strategy, where ‘coexistence’ rested uneasily with ‘nationalism’ and court politics. The humiliation of tribute, the massive defense budget eating up 80% of state expenses, and the demand to safeguard China’s honor against the barbarians were things so-called ‘appeasers’ had to navigate carefully lest they wound up in exile or worse. Lastly, by the 1230s the Song was also in administrative decay, with the countryside and ports dominated by influential landowner and merchant clans.

1230s – 1242: Song Attack and Mongol Defense

The Song policy of ‘coexistence’ had ensured the dynasty’s survival the past two times it had been tried: both the Khitan Liáo and the Jurchen Jīn, despite their military superiority, were paid off through tribute and ritual humiliation, and eventually they were destroyed by a new wave of nomads to their rear. A similar policy towards the Mongols might have been the easiest way to preserve the dynasty.

Instead, the Song went in the opposite direction. Contrary to their abilities and strategic orientation, they attempted to reconquer Northern China: first allying with the Mongols to eliminate the Jin, then attempting to exploit the political vacuum by supporting rebels and warlords against the Mongols, and finally attacking their old capital of Kaifeng in 1234.

Historians have interpreted these actions through the simple politics of nationalism, but the Song about-face might have also reflected confidence in their strategic position. They knew the Mongols had no naval capability – the Horde was unable to cross even the 500-meter-wide Ganghwa Strait in their war against Korea – and so the Song did not need to fear retaliation. Given this, there was no downside in trying to shape the situation in North China to the Song’s benefit – avenging past defeats, creating semi-independent buffer states, and even preventing refugees from flooding into the South.

But if these were the intentions, however, Song strategy could only be described as a failure. Firstly, the court did not pay attention to the navy, which spent most of the 1240s refitting and thus deprived the Song of their most effective asset. Secondly, instead of cementing Song control over the warlords, the Song army was used in a dash for the ‘prestige’ yet indefensible region of the Central Plains, with the predictable result of defeat at the hands of Mongol cavalry. Lastly, the Song attack violated their prior alliance with the Mongols, gaining a reputation for duplicity and diminishing the chances of a successful ‘coexistence’ in the future.

By contrast, the Mongols had a clearer view of things. Despite Song provocation, they stuck to their strategy of ‘One War at a Time’, focusing their efforts against Russia, Central Europe, and Anatolia. Recognizing their naval inferiority, they stuck to raiding the Song instead of conquest. And even these were not simply quests for plunder, but aimed at capturing siege and naval assets, as well as disrupting local productivity and stretching Song resources even further. By 1234, Sichuan had stopped contributing funds to the broader Song defense, and instead was demanding more and more resources from Hangzhou.

1247 – 1259: Flanking the Song

By 1247, the Mongols were ready for another crack at East Asia. This phase of the conquest from 1247 to 1259 can be seen as a grand strategic attempt to knock out all Song’s immediate neighbors and turn its western flank as a prelude to general conquest.

Güyük Khan began the offensive with a renewed campaign against Korea, finally making the country a vassal in 1258. Korea was a source of timber for the Song navy and also a potential launchpad for Song naval disruptions, something that had indeed been planned against the Jin in the 12^thC. Vassalizing Korea would allow the Mongols to do the same in reverse against the Song, but the flip side of this was that the country would also become a running distraction for the Mongols, dragging them into disputes within the royal family and with Japan.

Möngke Khan followed this up with an assault on Tibet and modern Yúnnán, with the former vassalized in 1253, the Kingdom of Dali conquered in 1256 and Vietnam vassalized in 1257. These were not minor efforts – 20% of the Mongols’ manpower, for example, was sent to Dali at the same time as the notorious campaign against Baghdad – and their aim was not just to cut the a source of horses for the Song, but to turn its entire western and southern flanks. The Mongols could then breach the Yangtze at its fordable upper reaches and, following its course, push the Song into the sea – eliminating the need for a navy, and the internal debates that would result from it.

Mongke’s flanking approach may have been politically sound but it was strategically dubious. Launching attacks across the jungles of Yunnan and Vietnam were non-starters, and fighting the Song along a 1000-km-long flank would have enmeshed the Mongols in a long war of attrition while compressing the Song into an ever-tighter, ever-more defensible perimeter. Fatally, Mongke also underestimated South China’s climate: having invaded the Song in early 1258, he fell ill and died 18 months later before the gates of Hézhōu in eastern Sichuan, only the first of the many Yangtze fortresses his strategy would have had him conquer.

1263 – 1273: The Siege of Xiangyang

The death of Mongke caused the tension between settled and unsettled Mongols to explode into open warfare, and as Kublai engaged a 3-year civil war from 1260-1263, the Song was given time to devise a response to the impending assault.

Song policy at this point revolved around Chancellor Jiǎ Sìdào, a corrupt and divisive but strategic leader. Leveraging his unearned prestige as a ‘victor’ over Kublai’s diversionary attack down the Han River in 1259, which in fact ended because Kublai left to seize his inheritance, Jia mobilized the Song for war, repairing fortresses and expanding the army and fleet. To fund this, he printed massive amounts of paper money as a form of public debt, and seized landowners’ and merchants’ assets, earning their hatred in a move that would have long-term consequences.

Ever since the 1240s the Mongols had fallen into chronic political instability and repeated succession crises, which argued in favor of continuing the Song approach of defense and attrition. Jia Sidao took this strategy to the max, ending Song engagements in North China in favor of fixed defenses and the riverine navy.

Of the three theaters of operations, Jia appreciated that the Mongols could not contest Song control of the Lower Yangtze, and that Mongke’s focus on Sichuan had proven to be a dead end. He therefore focused Song efforts on bolstering the fortress network of the Han River Valley, which he correctly judged to be the main theater in the next war. Whatever his moral failings, Jia Sidao understood Song’s strategic situation.

On the Mongol side, Kublai emerged in 1263 as Great Khan, but his authority beyond East Asia was nominal. But this also meant that he no longer needed to navigate the settled-unsettled debate within the Mongols, and his great project of building a strong navy could finally begin.

Kublai’s approach to the navy was multifaceted and multinational. Firstly, he adopted Chinese-style bureaucracy to build and maintain his navy. The actual fleets themselves were cobbled together by state-led programs and requisitions from vassals. Lastly, Kublai aggressively courted all sources of naval expertise, bidding aggressively for the services of shipwrights and sailors, all the while adopting pro-commerce policies to lure overseas merchants disgusted with Jia Sidao to his side. In 1268 the Mongol fleet numbered 500 ships; in 1270 it had 5000. Similarly, Kublai greatly augmented the Mongol army by further opening the ranks to conquered peoples, not least Han Chinese.

While Kublai’s naval policy yielded impressive results, the key element in naval warfare is not so much quantity but expertise and experience. As such, even when Kublai ordered the siege of the twin fortresses of Xiangyang and Fancheng in 1267, the Song would have had little to fear. They attempted diversions in other theaters, before eventually stopping as Kublai’s full focus on the twin fortresses became evident. Still, so long as Song retained their naval dominance over the Mongols, Kublai would make little progress in Southern China.

This did not make Jia Sidao complacent; on the contrary, he proposed putting Xiangyang under his direct supervision, which would have allowed Hangzhou to coordinate closely with generals on the front. Considering that the twin fortresses were but one part of a broader defense network and that Song strategy was based around using the network to inflict maximum attrition on Kublai’s army and state, this proposal ought to have been a no-brainer.

In the event, court politics led instead to the appointment of a political enemy of Jia’s, paralyzing the entire military command. This disastrous decision led to three effects that, in the collective, would eventually lead to catastrophe. Firstly, the strategic effects of Xiangyang’s resistance was now reduced to simply wasting the enemy’s time, instead of proactive efforts at overstretching and perhaps defeating the enemy.

Secondly, Xiangyang’s defense was not integrated within a broader defense-in-depth of the Han River Valley, wherein the Song’s extensive network of forts might have provided mutual support and the fall of one did not result in theater-wide collapse. It seems that the Song defense plan was based around this, given the existence of numerous rear-area forts such as Yǐngzhou, Shāyáng and Hànyáng. But without coordination, everything was staked on the defense of the twin fortresses, turning them into ‘prestige objectives’ which had to be held at all costs.

Lastly, as the siege dragged on, the defense of Xiangyang began imposing costs on the defenders as well. As the northernmost Song outpost, resupply of the twin fortresses meant a long and winding journey for relieving convoys, and as the Mongol fleet grew in size and confidence they began actively contesting the Han River. Slowly but surely, Song naval losses began to mount, and if the post-Xiangyang record of the Song navy is any indication, many of these losses were experienced crew, and their absence would be sorely missed in subsequent engagements.

At some point, the benefits of resupplying Xiangyang simply ceased to be worth the losses in experienced crew and the Song ought to have pulled back to more defensive positions, shortened their supply lines, and above all held back experienced crew in anticipation for defense at the Yangtze. But lack of coordination now meant that there was nothing behind the twin fortresses to fall back on, and in any case Xiangyang’s defense had become a political rather than strategic imperative.

The Song navy therefore wasted away in increasingly desperate attempts at relief, and one could interpret Jia’s infamous lethargy in the late stages of the siege as a secret wish to see the twin fortresses fall and relieve the Song of their strategic burden. Kublai’s importation of the Islamic counterweight trebuchet from the Ilkhanate may have finally caused Xiangyang’s surrender in March 1273, but the fortress had long before stopped making a net positive contribution to Song’s overall defense.

1274 – 1279: Fall of the Song

Xiangyang ought never to have been that important to the Song, but its long resistance did hinder Mongol efforts in more ways than one. Kublai had spent 4 years to gain a toehold in the Han River Valley, with Song armies in the East and West still posing a threat to his flanks, and these were 4 years in which he could have been conquering other states and distributing plunder to his supporters. The path to Southern China now lay open before him, but in order to achieve his ambition of conquest, Kublai had to ensure that no more Xiangyangs would occur.

In this Kublai’s new Yuán Dynasty held an unprecedented advantage: thanks to Song’s losses of experienced crew on the Han River Run, the Mongols now had local control over sections of the Yangtze River network and could viably contest Song control elsewhere.

Kublai wasted no time in exploiting his advantage: as the Yuan resumed its advance in October 1274, Kublai ordered his coastal fleet to begin contesting control of the all-important Lower Yangtze, disrupting Song commerce and communications and forcing the Song navy to stretch itself even thinner than it was already.

Having gained as favorable a force advantage as he was going to get in the Han River, General Bayan now waged a war of maneuver based around joint land-river operations, using the army to bypass forts, the fleet to isolate them, and their combined mobility to strike deep into Song territory before the defenders could react. By January 1275 Bayan had crossed the Yangtze, overcoming the last stand of Jia Sidao and the Huai Army at Dingjiazhou two months later, and as the cities of the Lower Yangtze surrendered, the road to the Song capital lay open before them.

Right at the point of triumph, however, Kublai allowed his strategic focus to wander, driven by the need to make up the plunder denied to his supporters as they sieged Xiangyang. Already in 1271 he had invaded Burma, and in 1274 attempted to coerce the Japanese into submission. Now, he redeployed his forces for a strike against the invading Chagatai Khanate.

It was a major strategic mistake. Anti-Mongol revolts erupted throughout the conquered territories, and despite Bayan’s return, the defeat of yet another Song fleet at Jiaoshan in July 1275 and the surrender of Hangzhou in 1276, the Song court had recovered its nerve sufficiently to spirit away two princes further south in a bid to keep resistance alive. The Mongols had failed to decapitate the Song leadership in one stroke, and now would spend 3 more years and much goodwill in suppressing the insurgency.

Still, having been put on the back foot, the Yuan were quick to regain the strategic initiative. In contrast to the insurgent armies whose instinctive focus was on the recovery of their home territories, the Mongols prioritized the political objective, which was the fugitive Song court. This was done through arms and diplomacy: brutal suppression and pincer movements down the Chinese coastline, while persuading merchants and landowners to abandon and isolate the Song court.

For the Song, their main strategic question now was on how to maintain relevance and legitimacy while the territory they controlled shrunk by the day. One option was to flee to Southeast Asia, particularly friendly Champa, and set up a Government-in-Exile backed by overseas Chinese. Such a strategy, however, would have eventually run up against the political and mercantile interests of both host and overseas Chinese, and in any case, Song assessments of the martial quality of Southeast Asians were not particularly positive.

Given the subsequent Yuan record in Southeast Asia, however, such a judgment was far too hasty. Already, the Mongols were experiencing significant command and control problems in the Chinese Far South, with Guangzhou rebelling no less than 5 times and the Song court able to travel for months on end without detection. A Song court that established itself in the mountainous Southwest and used irregular and mountain warfare to repel the Mongols could have been the basis for another ‘coexistence’ policy that would outlast the Yuan’s 97-year lifespan.

Ultimately, the Song court succumbed to fatalism and decided on a third ‘strategy’, which was making a last stand on the coast of Guangdong. The final battle at Yáshān in March 1279 resembled a ritual sacrifice in its waning moments, with the Song exiles committing mass suicide instead of surrender.

Conclusions

Kublai Khan may have destroyed the Song, but the latter continued to make trouble for the Yuan. Refugees from the conquest poisoned Yuan relations with the rest of Asia, notably the Zen monk Sogen who became spiritual adviser to the Japanese leadership, and the diaspora in Southeast Asia which fueled Champa and Vietnam’s successful resistance to invasion.

The conquest of the Song demonstrated the Mongol Empire’s superior strategy and operational methods. The Song, despite their resource advantage, were paralyzed by court politics, distracted by ‘prestige objectives’, and when push came to shove, did not manage to weave their economy, military and particularly navy into a coherent strategy.

By contrast, the Mongols recognized their shortcomings from the beginning and took pains to craft a strategy that would have them face the Song without the interference of other powers. Despite having little prior experience with the sea, they understood the importance of a navy and, once they built one, used it effectively to fulfill their operational and strategic goals. They understood the links between strategy, diplomacy, the economy and their internal politics and while they did not always get things right, they kept their focus on catching up to Song strengths and exploiting Song weaknesses. In such a way, the million-or-so Mongols were able to take over an Empire of 60 million.

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