In 1941, during the darkest hours of World War II, the American Crimefighters' Association was assembled to battle Axis agents in America and abroad. This loose assemblage brought together grim urban vigilantes, colorful patriots, and enthusiastic youngsters, all dedicated to the common cause of freedom and democracy. From their secret headquarters in Washington DC, the ACA answered the government's call and took on those cases too dangerous for the regular authorities to handle. With the war over, the ACA disbanded in 1945.
When members of a group calling itself the League of Alphabetical Madmen claimed responsibility for a number of unusual crimes in the early 1960s, a new group of heroes, this time calling themselves the Association of Costumed Adventurers, rose to the challenge. The group flourished throughout the 60s, but disbanded in the early 1970s when M-Force's problems caused many cities to pass "anti-vigilante" laws.
In 2005, a new group of heroes appeared, calling themselves simply the ACA.