After completing his university studies he became a journalist, and started his political activities as a member of the Hungarian Social Democratic Party.

Many of them, including Szamuely and Kun, joined the Soviet Red Army and fought in the Russian Civil War.

In January 1918, he resided in Moscow, where he worked with Kun to organize Hungarian prisoners of war who supported the Russian Revolution.

In February 1919, as the communists in Budapest became prepared to rebel against the Social Democrat-Communist coalition government, he wrote in the pages of the Vörös Újság (Red News): "Everywhere counter-revolutionaries run about and swagger; beat them down!

"[2] On March 21, 1919, a coup by the communist members of the coalition government established the Hungarian Soviet Republic, under the leadership of Béla Kun.

The Lenin Boys' activities were sometimes aligned with another paramilitary, the Red Guard, led by József Cserny, in which, on an armoured train they travelled the country.

The Social Democrats, who were also members of the Revolutionary Governing Council, pushed for keeping Szamuely and Cserny in check.

Therefore, the People's Commissar of Military Affairs at that time, Vilmos Böhm, ordered the dissolution of the paramilitaries and the tribunals at the end of April 1919.

He planned to assassinate Böhm, but by August 1919, the Hungarian Soviet Republic had ended after the Hungarian–Romanian War, and Szamuely was forced into exile.

Both Hungarian and Austrian authorities reported that Szamuely had shot himself while the Communist partisan who smuggled him across the border was searched.

[9] The wife of Béla Kun wrote in her memoires that Szamuely had told her of his plan to commit suicide if he was captured and had showed her a gun hidden in his clothes.