The 240 mm Howitzer M1 was designed and first built in 1941 and saw extensive use in World War II in Europe and the Pacific, then in Korea until ammunition supplies ran out, and later remained in service in the Republic of China. It was the largest field piece used by the U.S. except for naval ordnance, and the only larger howitzer built for the U.S. Army was the 280 atomic cannon, which was never put into action. In the late 1950's, when the Department of Army established Army Reserve units nationwide, Lewistown had one of these units; the 743rd Field Artillery was a Regular Army unit that included the local reserve unit of about 50 to 60 local young men, who trained on a 240 mm howitzer although it was never fired locally. After a short time as a training aid, Montana Army Reserve units replaced the 240 with 155 mm howitzers. This 240 was donated to the City of Lewistown in 1957 and placed on display there in 1959. The gun had a 240 millimeter bore, fired a 360 pound projectile, required a 22 man crew including the drivers of two wagons because the barrel was removed for transport and carried on its own wagon, had six men on the loading tray and four on the rammer staff, a range of about 14 miles, a muzzle velocity of 2300 feet per second, a weight of 64,700 pounds, and a barrel length of 27 feet 6 inches. Its loading operation was somewhat similar to a muzzle-loading rifle except that it was loaded from the breech: the projectile was loaded first, followed by powder bags, and the fuse to ignite the powder was a blank cartridge screwed into the breech.