Used as a 'Devilish Duo' the other part of the combination being the Churchill 'Crocodile' flame thrower.
the petard would hurl a shell to crack a bunker or reinforced strongpoint. The stunned unfortunates inside would be then immolated by a deluge of flame from the Croc; the flaming liquid seeping through the cracks or depriving those inside of oxygen.
My late father-in-law commanded a Croc in early 1945. He maintained that the knowledge of the mere presence of this inhumane weapon caused the demoralised German troops, at that late stage in the conflict poorly trained, sub-standard and often very young, to surrender or run.
A fellow commander was berated by an outraged Heer officer that the usage of the Croc was "unfair and un-British!"
I found it hard to associate this kind and gentle man I knew as a lovely caring Granddad to my 4 children with using such an awful weapon, though he claimed he never had to use it in anger. "I only burnt some old huts!" at Belsen Bergen perhaps? 7th Armoured were nearby, but grim faced he wouldn't expand further.
Postwar he went onto Comets, and armoured cars during the partition of India. When 7th Armoured was disbanded in 1957, he went into Air Despatch, retiring in 1972.