His contingent of 800 elite Mongol soldiers fought White Russian and Chinese forces over 30 times between 1912 and 1921, without a single defeat.

In the spring of 1913, Magsarjav commanded troops defending the southern border against Chinese incursions near Jingpeng and Dolon Nur in Inner Mongolia.

After Chinese troops under General Xu Shuzheng occupied Mongolia in 1919, Magsarjav was imprisoned in Niislel Khuree in mid-1920 on suspicion of having contacts with resistance groups headed by Sükhbaatar.

From March 1921, Magsarjav served as commander-in-chief of all Mongolian troops under Ungern von Sternberg's puppet government.

In May 1921, Magsarjav left the capital ostensibly to mobilize troops in Uliastai and western provinces to confront the expected invasion of Mongolian partisans (commanded by Sükhbaatar) and Red Army units.

At night to July 22, under the pretext of destroying Whites, Uliastai was seized, and a considerable part of Russian settlers and refugees were killed.

In 1923 anti-revolutionary resistance groups (made up mostly of troops formally under Ungern command), sought Magsarjav's assistance.

The Khalkhyn Tsereg were Magsarjav's most trusted contingent and entirely consisted of ethnic Khalha Mongol soldiers, recruits from various regions of Mongolia.

Though the actual geographic distribution is not well known, it is often speculated that they came mostly from today's Zawkhan, Tuv, Khuwsgul, Bulgan, Ömnögovi, Khovd, Arkhangai and Uvs provinces of modern Mongolia.

At the same time, Magsarjav with his detachment of 400 men very carefully pursued large White troop formations retreating from western Mongolia to Xinjiang: he waited for weapons from the Reds, as well as reinforcements.

The majority of the contingents of White Russians in western Mongolia were defeated with or without the support of Soviet Red Army, with most retreating to Xinjiang.

Khatanbaatar's fame of bravery and success were broadly publicized during the time of pro-communist rule in Mongolia, while negative sides of his activity were concealed.