Belgrade is currently the capital of Serbia. It has been the capital of the government ruling Serbia since 1804. From 1918 to 1941, and from 1944 to 2003, it was the capital of all three governments of Yugoslavia. From 1941 to 1944 it was the seat of the so-called "Government of National Salvation," a Nazi puppet state which existed during World War II, and from 2003 to 2006 it was the capital of the State Union of Serbia and Montenegro.
One of Bogdan's men had a cousin who owned a business in Belgrade. While the cousin was not part of their resistance movement, his existence was fortuitous because it gave the man an excuse to travel to Belgrade without arousing Croatian suspicion.