Even before the last Australian surrendered at Rabaul, the Japanese flooded New Britain with men, weapons, and material to enlarge the aerodrome, expand the port facilities, and turn Rabaul into a proper staging area for further campaigns in eastern New Guinea and the Solomon Islands, both scheduled for May. The harbor there was packed with Japanese transports waiting to unload. It was a ripe target.
In an attempt to replicate the Marshall/Gilbert raids, Nimitz directed Task Force 10, consisting of the aircraft carrier USS Lexington and her escort of cruisers and destroyers, to raid Rabaul. But the Japanese commander expected this, and his reconnaissance spotted the Lady Lex and TF10 450 miles out, well outside strike range for the carrier.
The Japanese commander launched all seventeen of his land bases G4M torpedo bombers, nicknamed “Betty” for their voluptuous figures. They had a much further range than anything the Lady Lex carried although they were armed with bombs instead of torpedoes because the torpedoes weren’t unloaded yet. As Halsey pointed out a few weeks before, American carriers were severely deficient in fighters. A proper CAP rotation (combat air patrol, the fighter screen charged with protecting the TF from air attack) required more fighters than the carrier had, much less those needed to escort the bombers. When the first wave of eight Betty’s approached, the Lexington’s CAP fighters and the ready fighters on deck screamed off and shot them all down. Unfortunately this left the TF defenseless (We will see this phenomenon again). The next wave of nine Betty’s approached from a different direction and had a clear run at the TF.
Luckily, there were two fighters from a previous CAP still being refueled on the deck. Their pilots, LT Edward “Butch” O’Hare (the son of Chicago gangster Al Capone’s lawyer), and his wingman jumped into their cockpits and took off. They had just enough fuel to intercept the incoming Japanese a few miles out.
The Betty’s were flying in a “V” of “V’s” formation which gave good overlapping fields of fire for their rear gunners. Nevertheless, O’Hare and his wingman pounced on them from above. All four of the wingman’s guns jammed, which left just O’Hare to defend the Lexington. With only 450 rds per gun or 32 seconds of continuous firing, he didn’t have the ammunition to shoot them all down. He would try though.
O’Hare dove into the Betty’s and in a feat of aviation gunnery and ammunition conservation unequaled in the Second World War, shot down five Japanese aircraft in less than four minutes, and damaged a sixth. All those extra hours on the range paid off. Multiple observers would point out that there were three burning Betty’s falling from the sky simultaneously. The last three were driven off by the TF’s anti aircraft fire, much of which was directed at O’Hare.
One .50 cal gunner on the Lexington was particularly irksome, and though he didn’t do any damage, he wouldn’t stop firing at him. When O’Hare finally landed, he calmly walked over to the gunner’s position and admonished the young man: First, for not knowing the difference between an American F4F Wildcat and a Japanese G4M Betty, and then for not actually hitting anything. If he didn’t straighten up, he would “report him to the gunnery officer”.
O’Hare was the first American “Ace in a Day” (from zero to five confirmed kills in a single day) and the first US Navy ace of the war. He would subsequently be awarded the Medal of Honor, and Chicago would name its new airport after him.