On 22 June 1944, the 456th Bomb Group began flying a four-box 40-aircraft diamond formation to concentrate its bombing pattern for greater accuracy. On 2 July, the group earned its second DUC on a mission to bomb the Shell Oil refinery at Budapest, Hungary. 31 aircraft bombed the previously-untouched refinery at mid-morning and three minutes after bomb release, before reassembly in the new formation, were attacked by 50 Bf 109s and 10 Fw 190s of Luftwaffe "gruppe" JG.302 and Hungarian Air Force 101 Puma Group. The second box of the 456th bore the brunt of the attacks, with the 744th Bomb Squadron losing six of nine bombers in the target area and a seventh damaged beyond repair. 36 airmen were killed or missing and 24 captured, the largest single-day loss for the group.