The 25 Pounder was the standard artillery piece of both the Royal Australian Artillery as well as the Royal Horse Artillery, the British Artillery Regiment, that aided the Australian Infantry with the defence of Tobruk during the siege by the Afrika Korps in 1941.
Several of these guns, along with countless crates of ammunition, were captured by the Germans at Mersa Matruh in Rommel's rapid advance towards Alexandria in 1942. These same guns were turned upon the 2/48th Infantry Battalion during the Battle of El Alamein with devastating effect. The 2/48th retook the guns within a short period of time and again set them upon the fleeing Germans.
All accounts from Tobruk that I have read all say that without the support of the Royal Horse Artillery the Siege of Tobruk would have been over very quickly. Tobruk was the perfect example of Australian Infantry and British Cavalry and Artillery working as one cohesive unit.
image courtesy of Robert Snewin. Used with permission.
This post is a direct reponse to the question asked by Douglas Chan who wanted to know what were the Royal Horse Artillery guns used during the Siege of Tobruk. I hope this helps Douglas. Good luck with your project!