Trench Mortar

Trench mortar crossword clue. The Big One no 5911 The Daily Telegraph (Sydney) on 16 May 2017. 8 letters

The answer is HOWITZER

Mortars are useful at much shorter ranges than howitzers or cannons. They fire at a very high trajectory and can be extremely useful when the enemy is close. They can also, as a result of the high trajectory, fire over immediately intervening obstructions like hills or buildings. Howitzers are more likely to fire through buildings and aren’t much good if the enemy is just on the other side of a hill in front of you.

Mortars are light weight weapons, usually for infantry use and normally use fin-stabilised ammunition. They fire at low velocities and can therefore have a thin and light barrel. They are also generally muzzle-loaded.
Howitzers are towed (or self-propelled) heavy-duty field pieces, breech-loading and capable of far longer ranges than mortars, firing shells from a rifled barrel.