During World War II, Jaskilka served aboard the USS "Princeton" and participated in the Tarawa Island raid, the Gilbert Islands Operation, the Marshall Islands Operation, Palau, Yap, Ulithi, Wolei raids, Marianas Operation, Western Caroline Islands Operation and the Leyte Operation. He served on the USS Princeton and survived its sinking in the Battle of Leyte Gulf On October 24, 1944. He was promoted to first lieutenant on June 22, 1943.