Against Japan, the M69 was carried in the bomb bay of the Boeing B-29 Superfortress, with a typical load containing 40 cluster bombs, a total of 1520 M69 bomblets. The bombs were very effective in setting fire to Japanese civilian structures in mass firebombing raids starting in February 1945 against Kobe. In the first ten days of March 1945, raids with the M69 and M47, extensive damage was done to Tokyo, to Nagoya, to Osaka, and to Kobe.