Developed in 1938 by the Glenn L. Martin Company as a long-range ocean patrol flying boat. The prototype, XPB2M-1, was launched on November 8, 1941. Following tests between 1942 and 1943, the Navy approved the aircraft for transportation. The aircraft had a crew of four, with accommodations for a relief crew, and was approximately 117 feet in length. Seven aircraft were produced, including the prototype, which was later scrapped in 1945 after transferring to Fleet Tactical Support Squadron 2 (VR-2) at Alameda, California. The aircraft mainly were utilized for trips back and forth to Hawaii from California. All, except for Hawaii Mars I, were upgraded to JRM-3.
The Mars aircraft in U.S. Navy service were named. Hawaii Mars I was first flown in July 1945 but later sank in August in the Chesapeake Bay and was scrapped. Philippine Mars was delivered in 1946 and flew with VR-2. Serving until 1956, she later became a forest fire fighting aircraft and is awaiting to be displayed at the National Naval Aviation Museum. Marianas Mars delivered in 1946 and assigned to VR-2 until 1956. Also converted to a forest fire fighting aircraft, she crashed on June 23, 1961, into Mount Moriarty near Nanaimo, Vancouver Island, killing her crew.
On April 5, 1950, Marshall Mars was destroyed by an engine fire and sank off Diamond Head, Oahu, Hawaii. Her crew of four survived, and her wreck was discovered in 2004. Delivered in 1946, Hawaii Mars II served with VR-2 until 1956 and later became a forest fire fighting aircraft and operated in the British Columbia area. She is the only Mars aircraft still in service. The last aircraft, Caroline Mars was delivered in 1948 and also served with VR-2. The aircraft also served as a forest fire fighting aircraft after her Navy service and was damaged beyond repair during Typhoon Freda in October 1962 at Victoria, Canada.
Image: NH 70215: Martin JRM-2 (Philippine Mars, BuNo 76280), 1947. In flight at NAS Alameda, California.