While in power, Ion Antonescu aligned himself with the Iron Guard, offering positions in his government and deceiving some leaders into supporting him. Antonescu sought to bring the Iron Guard under his direct control because their activities and sympathy for the Romanian people and their cause were undermining state authorities.

The brief period that followed became known as the Legionary National State, which lasted from September 14, 1940, until its dissolution on February 14, 1941, totaling only five months.

With the puppet state fully operational under the Germans and Antonescu's ambition, the two armies began to cooperate. After the capture of Bessarabia and Bukovina, Antonescu sent the Romanian army into Soviet territory, determined to follow the German troops until the complete conquest of the Red territory.

This decision was met with disapproval from the Romanian people and politicians, including those from traditional parties and the Allies. Although Antonescu had spent most of his life in the military career, he failed to adequately prepare the Romanian army for a prolonged campaign. After the Germans and Romanians suffered significant losses in the Battle of Stalingrad and the Russians began their offensive that would only end in Berlin, Antonescu's popularity, which was not the best, rapidly declined.