"Eastern Mandates" is a campaign credit entitlement covering the time frame 7 December 1943 to 16 April 1944, both dates inclusive. Anyone serving in any capacity within the prescribed area of operations in the Pacific Theater between the above dates is entitled to wear one bronze service star on the ribbon of the the Asiatic-Pacific Theater Medal. The qualifying period includes operations in the Marshall and Caroline Islands (including combat landings and operations at Kwajalein, Roi, Namur and Eniwetok). "GO 33 WD 45" (War Department General Orders Number 33 of 1945) is the official basis for issuance of the campaign credit.
Medium Tank Crewman 2736 was your father-in-law's military occupational specialty (MOS) and MOS identifying number.
The battalion was attached to the Fifth Marine Amphibious Corps and supported elements of the 2d and 4th Marine Divisions and the 7th Infantry Division during operations in the Marshall Islands.