I believe the tunnel served its purpose in saving casualties amongst runners, reserves hurrying up etc. I was advised to use it myself during a forward recce but having inspected the entrance decided on the open route across the top.⁶⁵

Harvey claimed in 1929 that one of the lessons of the Battle of the Somme was that ‘Russian saps have solved the difficulty of crossing No Man’s Land.’⁶⁶ This, however, was clearly not borne out by the experience of the Somme or of subsequent battles. GHQ reported on the value of the tunnels in the attack, giving recommendations as to their construction and reporting that their utility was greatest when the attack was temporarily held up:

The real use of these galleries is brought out when the infantry attack progresses very slowly. On the 13th November on that portion of the front at which the attack was successful, the advance was so rapid as to render these galleries unnecessary except in the case of the two tunnels, which were on the flank of the successful attack.

The reservations expressed by the Brigade Major of 188 Brigade were also addressed:

The infantry still appear to have a great prejudice against going down a tunnel and will only use it under strong provocation, but the utility of such tunnels has been proved and where they are prepared this disinclination on the part of the infantry should be overcome by preliminary explanation.⁶⁷

A 5th Army letter, probably drafted by Preedy, in response to a request for more information by the 1st Army, denied that such a prejudice existed.⁶⁸ It had not been conceived on 1 July 1916 that men could use the tunnels to emerge one at a time from easily observed tunnel entrances, although plans for troops to emerge from tunnels behind enemy defences were put forward after the war by fiction writers. The practical difficulties, evidently understood more clearly during the war, prevented this method from being attempted.⁶⁹ The report by GHQ on Russian saps, however, led to the most important uses of subways, as they came to be called, for the offensives at Arras and Vimy Ridge in April 1917 to assist passage to and from the front line and also to mass troops safely and secretly for the attack.