BL 4.5-inch Medium Field Gun

The BL 4.5 inch Medium Gun was a British gun used by field artillery in the Second World War. It had nothing in common with the QF 4.5 inch Howitzer or the QF 4.5 inch AA Gun.

History
The BL 4.5 inch gun was designed as a replacement for the 60-pounder. It was a long range medium gun designed for the Counter-battery fire mission and used throughout the Second World War in this role. It equipped a significant proportion of medium regiments, including half the Canadian ones.

The Mk 1 ordnance was designed to be mounted on the 60 pounder carriage. The Mk 2 was on a new carriage that was also used with the BL 5.5 inch gun that replaced the 6 inch howitzer. There were slight differences in the Mk 1 and Mk 2 ordnance but maximum range was almost identical.

The Mk 1 gun was first issued in 1938 and equipped one or two regiments of the British Expeditionary Force. They also equipped at least one regiment in the North Africa campaign and some were lost in Greece. The 4.5 inch Mk 1 is sometimes mistaken for the 60 pounder. Both Mks were normally towed by the AEC Matador 4 x 4 medium artillery tractor.

Issues of the Mk 2 ordnance on the common carriage started in 1941 and served in North Africa, Italy and North West Europe. It was withdrawn from field service in 1945 and relegated to training purposes and finally declared obsolete in 1959.

The US 4.5 inch gun M1 used the same shell design, Mk 1D in UK service with a 6/10 crh. This design was noted for its small amount of HE (3.9 lbs in a 55 lb shell) but the larger fragments that resulted were suited to its counter-battery role. Apart from HE the only other type of shell was flare used to indicate targets for air attack. It had propellant in charges 1, 2 and 3.

Intense rate of fire was 2 rounds per minute, Normal rate was one round, Gunfire was 2 to 3 rounds per minute.

Variants

 * Mark 1
 * New 4.5 inch ordnance on 60 pounder carriage introduced in the 1930s used by the Royal Artillery in France and North Africa in the Second World War.


 * Mark II
 * Modified ordnance on Carriage 4.5 inch and 5.5 inch in use in the Second World War from 1941 by British and Canadian artillery.