Two days following the attack on Clark Field, the remnants of the Group attacked and destroyed one troop transport and severely damaged another while the Japanese fleet was off the Philippine coast in preparation for an invasion. For the next two weeks, the 19th fought heroically in a series of small, but effective, strikes against the enemy. However, in the face of insurmountable odds, on 24 December 1941, the 19th Bombardment Group withdrew to Australia. It was aboard one of the 19th's aircraft that General Douglas MacArthur evacuated the islands.

The remaining personnel of the 19th joined in small bands with service personnel in guerrilla actions hampering the Japanese occupation of the islands. Others were captured by the enemy and forced to partake in the infamous Bataan Death March.

Records of the 19th prior to 1941 are sketchy due to most being destroyed while at Clark Field. From Australia, the 19th went, as part of a joint allied command, to the Dutch Indies to participate in the defense of Java. Although the allies put up a stiff resistance, they again withdrew to Australia in March 1942.