From Batchelor Field near Darwin, Australia, the 19th conducted operations against the enemy. The group was suffering from such severe personnel shortages that crew members serviced their own aircraft prior to missions. It was from Batchelor Field in May of 1942, the 19th launched strikes in support of the first significant allied victory in the Pacific, the Battle of the Coral Sea.

Following this victory, the 19th started flying what are now termed as interdiction missions against the enemy. Supply routes became the major targets of the 19th during this period. Rabaul, a key point in the Japanese supply lines, was bombed with increasing frequency by the 19th during the spring and summer of 1942. The group flew the largest single bombing attack against the Japanese, up to that time, on April 1, 1942. This attack was in support of the U.S Marine's invasion of the Japanese fortress on Guadalcanal. The mission of the 19th was to destroy the Vanakanau airdrome at Rabaul. During the attack, the 19th destroyed fifty enemy aircraft on the ground and seven pursuit aircraft in the air as well as severely damaging the airdrome area.