In 1911, Römer began his career as an officer and was promoted to the rank of Captain during World War I. He was one of the leaders of the Oberland Free Corps in 1919, and he participated in the suppression of the Munich Soviet Republic. Subsequently, he studied law in Munich, received his doctorate in Würzburg in 1922, and worked in a variety of companies. While doing so, he also wrote articles for the right-wing newspaper Die Neue Front (The New Front). In the late 1920s, Römer drew ever closer to national-revolutionary movements until he finally switched sides and became editor of the newspaper Aufbruch, with which the KPD aimed to gain influence in right-wing national-revolutionary circles.
After the Nazis seized power, Römer was arrested and imprisoned in Dachau Concentration Camp and Columbia Concentration Camp, among others. After his release in July 1939, he got in contact with Hans Hartwimmer , whom he knew from the ‘Oberland League’, and encouraged him to set up an illegal organization together with former Oberland members and communists. Römer was the strategic head of the later so-called Hartwimmer-Olschewski group, which was named after its most important protagonists. He believed that the war could never be won, therefore the revolutionary cadres had to be formed now. These cadres would assume power upon the collapse of the regime and establish true socialism in alliance with the Soviet Union. Römer, who lived in Berlin from 1940, also established contact with a large Communist group operating in Berlin (Robert Uhrig group). In February 1942, the Munich group was rounded up by the Gestapo. Römer was sentenced to death for high treason and executed on September 25, 1944.