The National Pacification Army (NPA), also known as the Anguojun or Ankuochun (Chinese: 安國軍), was a warlord coalition led by Fengtian clique General Zhang Zuolin, and was the military arm of the Beiyang government of the Republic of China during its existence.

[1]: 18  The NPA suffered a series of serious military defeats inflicted by Chiang and his warlord allies, including Feng Yuxiang, Li Zongren and Yan Xishan.

Following the National Protection War against Beiyang Army general-turned-emperor Yuan Shikai, China became balkanized into a collection of regional power networks, the feud between different factions intensified, and warlordism was born.

The decisive moment of the conflict came on 30 October 1924, when warlord Feng Yuxiang broke from the Zhili clique, declared the establishment of the independent Guominjun, and aligned with the Fengtian in his Beijing Coup.

[6]: 164–165  This led to an overwhelming Fengtian victory, the removal of the Zhili clique from the capital and Cao Kun from the presidency of the Republic of China, and placed Zhang Zuolin in control of the Beiyang government.

Both had been seeking an alliance with the Zhili clique, but Wu Peifu, in an attempt at revenge, sided with Zhang in the Anti-Fengtian War.

In January 1926, Zhang launched an offensive, ordering his troops in Fengtian and Shandong provinces to invade Beijing and Tianjin.

This posed a serious threat to the northern cliques, and countering the Kuomintang advance would be the raison d'être of the National Pacification Army.

[1]: 112–13 Following the period of chaos in the aftermath of the Anti-Fengtian War, and the disintegration of Guominjun and Zhili power in Beijing, Zhang Zuolin brought together his Fengtian Army commanders and other, non-affiliated warlords such as Sun Chuanfang and Yan Xishan in November 1926 to discuss the situation.

[9]: 96–97  According to historian Donald Jordan, the name "National Pacification Army" is rooted in "engaging in war to achieve peace", a traditional idea in China's long history of dynastic leaders fighting to reunite the country.

At the time of the NPA's establishment, Zhang Zuolin vowed to save China from the "red menace", an attack on the Kuomintang's United Front with the Chinese communists, and their Soviet and Comintern backers.

[1]: 67  Zhili clique general Wu Peifu was considered a part of the NPA, but his power-base was destroyed when the KMT conquered Hubei province in late 1926.

[8] The NPA was essentially a new version of Zhang Zuolin's Eastern Three Provinces Defense Headquarters, with its main difference being that it was located in Beijing, rather than Mukden (now known as Shenyang, formerly known as Fengtian).

In May 1927, the Japanese, represented by Colonel Doihara Kenji, sent a message to Shanxi warlord Yan Xishan, asking him to establish peace between the NRA and the NPA and "take over northern China".

[13]: 317–8  The Fengtian clique declared that Zhang Zuolin would be elected president of the Beiyang government once the provinces north of the Yangtze River were secured.

By August, the front line had moved to southern Jiangsu, with the NRA being pushed to Nanjing, leading Yan Xishan to revert to neutrality.

This tipped the balance, and Yan began an offensive along the Beijing-Suiyuan Railroad in October, opening up a new front of fighting between the KMT and the Anguojun.

Gaining international recognition was crucial to the Beiyang government, as it would add another layer of legitimacy and help reverse the unequal treaties, which was one of the main goals of the Kuomintang movement against the warlords.

Ignoring his differences and disagreements with Zhang Zongchang and his 150,000 men in Shandong, Sun joined him in attempting to push the NRA back.

The coalition between Chiang, Feng, Yan, and Li Zongren surrounded it to the south, with troops in Shanxi, Henan, and southern Shandong.

Having observed the dire state of affairs of the NPA in Beijing, feeling alarmed at the potential fate of Japanese interests in Manchuria should the Kuomintang be victorious, and believing that Zhang was too uncooperative, officers of the Japanese Kwantung Army threatened that they would block Zhang Zuolin from returning to Mukden if he made an agreement with the KMT.

[17] As he was returning to Manchuria following the abandonment of Beijing, his train was blown up by officers of the Kwantung Army on 4 June 1928 in what was called the Huanggutun incident.

Yang Yuting became fully responsible for the military strategy of the NPA, which had now been severely reduced, assuming the role of Commander-in-Chief of the Eastern Three Provinces Defense Headquarters in July 1928.

[18] Zhang therefore ordered the executions of Yang and his associate, Heilongjiang governor Chang Yinhuai,[19] thereby ending the leadership of the internal clique of Fengtian officers that had attended the Imperial Japanese Army Academy and allowing Zhang to take full control over the affairs of the Fengtian clique and the NPA.

[20] Zhang Xueliang decided to cut down the Fengtian Army and funding to the Mukden Arsenal to fix the financial situation of Manchuria.

In its place, local warlords began to dominate Manchuria; the people of the northeastern provinces suffered from increasing societal disorder, and Chinese authority collapsed in the region, paving the way for the 1931 Japanese invasion following the Mukden Incident.

There were also 4,000 White Russian mercenaries serving in the army, and 2,000 boys (ages averaging around 10) led by one of Zhang Zongchang's sons.

[23] Zhang Zuolin, as he saw himself as lacking the political power, styled himself as Generalissimo, rather than President as Sun Yat-Sen had done, from the start of the military government in 1927.

Popular pro-Ankuochun slogans included: "May the Chinese Republic live thousands of years", "Eliminate violence at home", and "Counter foreign aggression".