[Title: The German retreat and the great Canadian victory at the Battle of Arras, part 4]: ELSs of battlefield at Arras, shells exploding, Cameronian soldiers racing across no man's land during raid on German trenches. MS of Canadian soldiers fixing up ladders in trench in preparation for attack. HAMS of Canadian cavalry company moving by camera at moderate pace. HA PAN view of cavalry standing by in a field. Sequence showing observation balloons being inflated, observer posing with security harness on, LAS of balloon ascending. HAS of launching site seen from observation balloon going up. Vertical LAS of observation balloon being winched down slowly. LALSs of aircrafts flying around observation balloon in the sky. Low level AERIAL SHOT of Arras railway station and surroundings. CS of observer in gondola of balloon speaking on telephone. MS of soldier receiving call, other soldier speaking through megaphone to artillery crew ready to fire in background. MLS of artillery crew firing 4.7" field gun. LS of explosions on battlefield. [Titles interspersed]