Training in minor tactics, 2nd Army Bombing School, Western Front, probably early 1917.
A series of explosions in an open field (no indication of scale). British gunners loading and firing a 9.45-inch 'flying pig' mortar, repeated several times and filmed from various angles and distances to show the variations in explosions. Helmeted British (or Australian ?) soldiers coming over the top from a training trench moving in single file. Others, some in slouch hats, stay in the trenches. Several more stock explosions providing a barrage. The advancing troops arrive at the ground, cratered from the barrage, and start to dig in and wire the position.