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Godefroy (2008) suggests (p235) that the trench warfare on the Western Front was the result of Germany's war with Russia in the East - they were unable to wage aggressive war on two fronts. And the invention of machines guns and the artillery of the time meant that the Front "soon settled into a series of largely static front lines that required... new ideas in order to break through them" (p236).
"Trench raiding was essentially any raid or minor operation whose purpose it was not to take ground from the enemy and hold it, but rather to complete smaller objectives against the enemy such as inflicting casualties, destroying enemy equipment, collecting intelligence, creating deceptions, lowering morale and, in general, cause havoc within the enemy lines." (P238) An order in 1917 gives details of the trenches to be raided, and the time, "ZERO HOUR plus 4 minutes", and that the "attacking party" will act "for the purpose of inflicting casualties, making prisoners, securing booty and wrecking dugouts". (P238)
Documents captured might give valuable intelligence. The raid might provoke a counter-attack, which could be met with artillery, increasing casualties.
One of first trench raids was carried out by 2 battalions of the Gerwhal Rifles of the Lahore Division against German lines on 9/10th November 1914, (p239).
Trenches were 4-6ft wide, and 6-8ft deep, in a zig zag pattern. German trenches "were often more solid and complex", with forward ammunition dumps and concrete bunkers. (p241).
[To Be Continued]
REFERENCES & Further Reading
Godefroy, A. (2008) Daring Innovation: The Canadian Corps and Trench Raiding on the Western Front. In B. Horn & O. Lavoie (Eds.) Show no Fear: Daring Actions in Canadian Military History (pp235-266). Toronto: Dundurn Press.
Rawling, B. (2014). Surviving trench warfare: technology and the Canadian corps, 1914-1918. University of Toronto Press.