When the Roter Frontkämpferbund was banned in 1929, he joined the Combat League against Fascism (Kampfbund gegen den Faschismus [de]).

Raab lived underground with a group of comrades, initially in the Beuerberg area, later in Antdorf and Hohenkasten.

At the end of 1933, Raab was in Bichl and was recognized by a Penzberg businessman who had been a member of the Nazi Party since January 1933.

Raab fled with a comrade on his motorbike to Austria, where he hid for a few weeks in the Karwendel Mountains, and then moved on to Switzerland.

[4] Raab was commander of the Thälmann Battalion from February to May 1937 and again from July 1938 to January 1939; holding the rank of major.

[5][6] After the defeat of the Spanish Republican Army, Raab crossed the Spanish-French border at the Pyrenees with the XI International Brigade on February 9, 1939.

[3] The internment camp was an open area in the sand dunes near the sea, fenced in with barbed wire.

[7] After the fall of France in 1940, the armistice of 22 June 1940 stipulated that all Germans in French custody were to be handed over to Germany.

After the liberation of Paris in the summer of 1944, he joined the Committee for a Free Germany for the West (Komitee Freies Deutschland für den Westen).

With the support of local mine workers, he was appointed acting mayor of Penzberg by the American occupation authorities.