Extensive land-based Combined Bomber Offensive bombings of German targets had begun in June 1943, followed by "Crossbow" operations attacking German long range weapon facilities in August 1943 and V-1 launch sites in December 1943. In July 1944 after the V-1 "Robot Blitz" had begun on 13 June, Commander Thomas Hinman Moorer of the Naval Air Atlantic Staff (NavAirLant) provided a Pentagon briefing on a June 1944 plan for F4U squadrons of Marine Air Group 51 (MAG-51) (including VMF-511, VMF-512, VMF-513 and VMF-514) to attack V-1 launch sites from escort carriers in the North Sea with Tiny Tim rockets. The Tiny Tim was a rocket power adaption of a 500lb bomb - each aircraft carrying a single rocket. The plan was disapproved. Project Danny was a victim of the intense interservice rivalry that existed in the US armed forces during World War II; Army Chief of Staff General George Marshall stood up and walked out of the briefing: "That's the end of this briefing. As long as I'm in charge there'll never be a Marine in Europe."