Editing Tumu Crisis (section)

===Mongol invasion===
[[File:MongolArcher.jpg|thumb|left|A Mongol horseman. Miniature from the 15th–16th century.]]
In July 1449, Esen launched a large-scale invasion of China, with the Mongols advancing in three directions. [[Taisun Khan|Toghtoa Bukha Khan]] and the Uriankhai attacked the [[Liaodong Peninsula]] in the east, while the second Mongol army advanced on Xuanfu and the third, led by Esen himself, advanced on Datong.{{sfnp|Twitchett|Grimm|1988|p=322}} The main objective of this campaign was to capture the fortified cities of Xuanfu and Datong, which would grant the Mongols unrestricted access to the northern regions of China.{{sfnp|de Heer|1986|p=20}}

On 20 July, news of the raid reached Beijing and the emperor responded by ordering four generals and 45,000 soldiers from the Beijing garrison to advance to Datong and Xuanfu to protect the border.{{sfnp|Goodrich|Fang|1976|p=290}} After learning on 30 July that Esen had already attacked Datong, Emperor Yingzong ordered the mobilization of the Beijing garrison. He also declared his intention to personally lead a punitive expedition without consulting his ministers.{{sfnp|de Heer|1986|p=16}}

Emperor Yingzong was known for his love of military parades, often organized for him by Wang Zhen.{{sfnp|de Heer|1986|p=16}} His self-confidence was further bolstered by the recent successes of the Ming troops in the [[Luchuan–Pingmian campaigns]] and in suppressing the [[Deng Maoqi rebellion|rebellion of Deng Maoqi]].{{sfnp|de Heer|1986|p=15}} All previous Ming emperors, except for [[Jianwen Emperor]], personally led armies into battle. Therefore, Wang Zhen used this to support the emperor's decision.{{sfnp|de Heer|1986|p=16}}

The first to protest were Minister of War Kuang Ye ({{zhi|t=鄺埜}}) and his deputy [[Yu Qian]].{{efn|Both had long warned of the danger posed by the Mongols, but their requests for stronger defenses were consistently rejected.{{sfnp|de Heer|1986|p=16}}}} They believed that the monarch's participation in a punitive expedition was an unacceptably risky adventure.{{sfnp|de Heer|1986|p=16}} Other officials also attempted to dissuade the emperor from joining the campaign. Minister of Personnel Wang Zhi ({{zhi|c=王直}}) wrote a memorandum on behalf of the dissenting officials, arguing that officers were responsible for the dangers of war, and the emperor, as the head of the [[House of Zhu|imperial family]] and the empire, and the person on whom the world's attention was focused, should not expose themselves to danger. Although the emperor appreciated his concern, he remained determined to carry out his plans.{{sfnp|de Heer|1986|p=17}} The last attempt to stop the emperor was made by a supervising secretary as the army was leaving the city. He threw himself in front of the emperor's [[Litter (vehicle)|palanquin]], but was unsuccessful.{{sfnp|de Heer|1986|p=17}}

On 3 August, Esen's army defeated the poorly supplied Ming army from Datong at the Yanghe Pass.{{sfnp|Twitchett|Grimm|1988|p=324}} On the same day, Emperor Yingzong appointed his younger brother Zhu Qiyu, Prince of Cheng, to oversee the administration of the capital during the campaign. Zhu Qiyu was assisted by four representatives from the most influential power groups. These included Prince Consort Commander Jiao Jing ({{zhi|c=焦敬}}), who represented the imperial family; [[Jin Ying (eunuch)|Jin Ying]], the head of the Directorate of Ceremonial and the highest-ranking eunuch in the absence of Wang Zhen; Minister Wang Zhi, who led the government; and Grand Secretary Gao Gu ({{zhi|t=高穀}}). All major decisions were to be postponed until the emperor's return.{{sfnp|de Heer|1986|p=17}}

Despite the deteriorating security situation, the emperor made a sudden decision without any prior preparations. This left the soldiers with only a few days, from 1 to 4 August, to get ready for the campaign.{{sfnp|de Heer|1986|p=17}} The emperor was accompanied by twenty experienced generals, most of whom held noble titles, and an equal number of high-ranking officials. They were also accompanied by hundreds of lower-ranking dignitaries,{{sfnp|Goodrich|Fang|1976|p=290}} with Wang Zhen serving as the ''de facto'' commander-in-chief.{{sfnp|Twitchett|Grimm|1988|p=323}} While the number of mobilized soldiers is unknown, it is often estimated to be around half a million,{{sfnmp|1a1=Goodrich|1a2=Fang|1y=1976|1p=290|2a1=Nolan|2y=2006|2p=151|3a1=Bennett|3y=1998|3p=323}} but in reality, the actual number may have been significantly smaller.{{sfnp|de Heer|1986|p=17}} Even under optimal conditions, supplying such a large army would have been challenging. The troops were hastily assembled, poorly supplied, and incompetently led, ultimately leading to disaster.{{sfnp|Goodrich|Fang|1976|p=290}}