Lapham joined Major Claude A. Thorp in organizing a raiding party that would slip through Japanese lines, sabotage Clark Field and gather intelligence for General MacArthur.: On January 27, 1942, they passed through Japanese lines into the Zambales Mountains, finally reaching Mount Pinatubo, where they established Camp Four or Camp Sanchez, and the newly promoted Lieutenant Colonel Thorp established radio communication with Bataan.: After the fall of Bataan, Thorp released his approximately one hundred men from following his orders, allowing them to surrender, stay or follow their own path.: