75mm Pack Howitzer M1

The 75mm Pack Howitzer M1 was a successful design produced in the early 1920s and that saw significant service in the Pacific, with US and British airborne forces into the 1960s and as a lend lease weapon.

Work on a new pack howitzer began in response to the Westervelt Board of 1919, which had produced a list of guns that would be required by the post First World War US army. Amongst them was a pack howitzer capable of being dismantled into several mule loads, for use with mountain troops.

75mm Pack Howitzer firing at Mt Tambu

A first version was developed in 1920, but this was rejected. A second, much improved, design first appeared in 1922. The army’s ten year ordnance plan of 1925 asked for 48 guns, to equip two regiments. The howitzer was standardised in August 1927 as the Howitzer, Pack, 75mm M1 on Carriage M1, but funding was limited. By 1933 only 32 had been built or funded and only 91 had been built by 1940.

The 75mm pack howitzer was a successful design. It used a sliding wedge breech, fired the same shell as the standard 75mm field gun and had a range of 9,600 yards, well ahead of the range required by the Westervelt Board. The gun was kept in place by a ‘top sleigh’, made of steel and lead, carried above the barrel. The original Carriage M1 had standard spoked wooden wheels, and a lightweight box trial with holes along the sides to reduce weight. It could be split up into four mule loads.

In the 1930s a new carriage with pneumatic tires and new axles bearings was developed, and was standardised as the Carriage M8. This was produced for use with airborne troops, but became standard equipment. An improved version of the gun was also produced, with a better breech ring and breech block, entering production as the M1A1.

The M1A1 entered full production in September 1940, and by the time production ended in December 1944 a total of 4,939 M1A1s had been built, mostly using the Carriage M8 (36 in 1940, 188 in 1941, 1,208 in 1942, 2,592 in 1943, 915 in 1944)

The pack design also impressed the US Cavalry, which asked for a version with a non-dismantleable carriage that could be towed at high speed. This was produced as the 75mm Howitzer M1 on Carriage M3, but was produced in much smaller numbers, with only 349 being built.

The 75mm pack howitzer entered combat on the Philippines in 1941-42. At its peak the 75mm pack howitzer M1 was used by 36 artillery battalions on 1944-45, mainly the artillery battalions of airborne and mountain divisions. Between them these types of units had twenty two divisional battalions in Europe and three in the Pacific. It was also used by two non-divisional field artillery battalions in Italy and four in the Pacific.

In the summer of 1940 the US Marine Corps decided to replace their French 75mm M1897 guns with the 75mm pack howitzer. In February 1941 they adopted a new divisional organisation in which each division got an artillery regiment with three 75mm pack howitzer battalions. By the invasion of Saipan that had changed to two 75mm and one 105mm howitzer battalions. By Iwo Jima one 75mm battalion was left in each artillery regiment, where the gun was nicknamed ‘Tiny Tim’. It served with the 1/11th Marines on Iwo Jima, where its small size and good ammo supplies made it a popular weapon.

The 75mm Pack Howitzer was given away under the lend lease programme in larger numbers than any other type of American artillery. 826 went to Britain, 637 to China, 68 to France and 60 to various partners in Latin America.

The pack howitzer remained in use with British and American airborne forces into the 1960s.

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