Ioakim Vatsetis was born into a peasant family in the Courland governorate. In 1891, he entered military service. He graduated from the Vilna infantry cadet school (1895), and the Nicholas General Staff Academy (1909). He was a participant of World War I with the rank of colonel (1915).

Vatsetis welcomed the February Revolution of 1917. He advocated national autonomy to be granted to Latvia. After the October coup of 1917, he went over to the side of the Soviet regime along with the 5th Latvian Zemgale Riflemen Regiment, which he commanded. He took part in the seizure of the Headquarters of the 12th Army, and in November 1917, he was appointed its commander.

In December 1917, he was appointed Chief of the operational department of the Revolutionary Field Headquarters at the Stavka [Headquarters]. Since January 1918, he was Commander-in-Chief of the Red forces directed against the 1st Corps of the Polish Army of Jozef Dovbor-Musnitsky. Since April 1918, he was the commander of the Latvian Riflemen division. In July 1918, Vatsetis was involved in the suppression of the actions of the Left Social Revolutionaries in Moscow.

Since July 1918, he was Commander of the Eastern Front of the Workers’ and Peasants’ Red Army. From September 2, 1918, to July 9, 1919, he was the Commander-in-Chief of the Armed Forces of the Republic. In January – March 1919, he held the post of the commander of the Army of Soviet Latvia.

In July 1919, Vatsetis was arrested on charges of treason but was released in August. In October, the charges against Vatsetis were dropped. However, he was not reinstated. Since November 1919, he was at the disposal of the Chairman of the Revolutionary Military Soviet of the Republic, Leon Trotsky. In 1921, he taught at the Red Army Military Academy and became a professor (1927). He wrote books on military skills and the history of the Civil War. Vatsetis was awarded the Order of the Red Banner (1928). The Commanding officer of the Army 2nd class [Komandarm 2nd rank].

In 1937, he was arrested and in 1938 he was convicted and shot on charges of espionage and alleged participation in a counter-revolutionary terrorist organization. He was rehabilitated in 1957.