Finding one’s way around is a constant preoccupation in memoirs of the First World War. James Robert Johnston of the 14th Machine Gun Company horse transport wrote “two of us with pack horses went up almost to the ridge (Vimy) and once got lost. (This seems to be an old habit of mine, getting lost, but I guess most everyone else had the same trouble.)” [Riding into war, 42]. The landscape of the trenches changed with each shell burst, and markers that might have existed to show the way were frequently obliterated as quickly as they were put up. The fact that most trench activity, such as reliefs, scouting expeditions, and supply deliveries, occurred at night made the situation even worse, since no lights were allowed.
Poor terrain intelligence was not only annoying, but deadly during pitched battle. Particularly in the early years of the war (1915-1916) when the lower ranks did not receive maps objectives were frequently confused, rising to situations like that at St. Eloi, when the 2nd Division CEF spent the better part of a week battling for what they thought were Craters 4 and 5, which were found to actually be secondary craters created during the earlier British battle for the same area that did not appear on their maps and were not their original objectives at all. The situation at St. Eloi was eventually partially rectified using aerial observation once the poor weather that had plagued the 2nd Division had cleared; planes were able to pinpoint exactly where the craters were and revealed that the Germans actually controlled most of the critical 7.
Solutions to the problems of location were applied throughout the war by the Allies through a system of trial and error. Airplanes, initially thought to be less than useful and faddish, were used frequently for the dangerous task of mapping the ever shifting trenches. Tethered hydrogen balloons were also used, as was simple on the ground observation by company scouts and observers. The map above is a hand drawn by Lieutenant (later Captain) Ralph Richmond Layte of the 85th Battalion of his lines near Vimy in March 1917. Layte may have gathered intelligence himself or had one of his scouts report to him, often these on-the-ground maps were much more accurate than the trench maps supplied by HQ.
One of the most effective solutions to the navigation problem was simply to allow the lower ranks maps. After 1916 and the failures on the Somme it became clear even to High Command that even the lowliest infantry soldier needed to know exactly where he was going and how to get there. This prevented the inevitable devolution of the lines that occurred during the Somme, when officers were killed and the lower ranks halted and dug in because they did not know where they were going. During the 4 month preparation for Vimy Ridge one of the things insisted on by Currie and Byng was the supply of accurate maps. Veterans of the attack later commented that this was one of the first instances where they knew their objective, and the confidence they felt in being able to respond to the split second changes during the actual day of battle.
After 1917 daily aerial observation, on the ground surveys and the distribution of maps were commonplace amongst the BEF and Dominion forces. That’s not to say that situations like that at St. Eloi the year before didn’t arise; the combination of weather and terrain at Passchendaele for instance made maps almost useless, but overall in the later years of the war the challenges of observation and mapping had largely been overcome. This would be particularly important during the final 100 days of the war, when the static war of the last 4 years suddenly became a series of moving pitched battles. By this time, intelligence was able to respond quickly to the changes in terrain and map areas that the Allies had not seen since the German lightening advance past Mons in 1914. The principles learned in the First World War, including to necessity for up-to-date observation and maps for every person involved in an action are still used today in modern warfare.
NB: The first iteration of this article wrongly listed hydrogen-filled observation balloons as hot-air filled. Many thanks to Gord Crossley of the Fort Garry Horse Museum and Archives for the fact check.