Project: Rebirth began as a collaboration between US, British and German eugenicists led by Dr. "Josef Reinstein" (real name Dr. Wilfred Nagel), and Dr. Koch. When WW II began, Koch took over the German program and Josef Reinstein took over the American program. Each was attempting to re-create the super soldier serum which had previously turned Steve Rogers into Captain America a year prior to Pearl Harbor. Reinstein's early attempts to refine the formula were tested on African-Americans. Three hundred of these soldiers were taken from Camp Cathcart and subjected to potentially fatal experiments at an undisclosed location in an attempt to re-create the Super Soldier formula, as seen in Truth: Red, White & Black. Only five subjects survived the original trials. In the name of secrecy, US soldiers executed the camp's commander and hundreds of black soldiers left behind at Camp Cathcart. The government told the families of the three hundred subjects that their loved ones had died in battle.

The sole survivor of his test group, Bradley stole a spare costume intended for Captain America before he engaged in a suicide mission to destroy the Super-Soldier efforts of the Nazis at the Schwarzebitte concentration camp. There, he was also able to assassinate Koch. The mission ended when the Germans captured Bradley. Nazi interest in the American supersoldier was high; he was even brought before the Fuhrer himself. Bradley was later rescued, only to be court-martialed and imprisoned at Leavenworth around 1943. In 1960, Bradley was pardoned by President Eisenhower and released.

Considered to be the "Black Captain America", Isaiah Bradley became an underground legend among much of the African-American community in the Marvel Universe. A number of the most noted Africans and African-Americans of the twentieth century's last four decades visited Bradley as a sign of respect and, in many cases, hero worship. His visitors have included Malcolm X, Richard Pryor, Muhammad Ali, Angela Davis, Alex Haley, Nelson Mandela, and Colin Powell. Outside the Black community, however, he remains largely unknown. When he arrived as a special guest to the wedding of Storm and the Black Panther, several African-American heroes were awestruck, including Luke Cage, Giant-Man (Bill Foster), Monica Rambeau, Triathlon, and the Falcon. However, the Canadian-born (and white) Wolverine was totally unaware of the man's identity or importance.