How would a modern Channel Tunnel transported to September 1914 affect logistics and the submarine campaign?
Short answerMost personnel could move safely by rail beneath the Channel, reducing submarine leverage, while ships would retain part of the freight burden and engineers adapted the tunnel's electrical systems.
NotesA working Channel Tunnel in September 1914 would sharply reduce the submarine threat to troop movements by putting most personnel trains underground. Freight would still use ships where that was simpler, while sustained tunnel throughput would require careful train spacing and adaptation of a system designed for electric traction to contemporary power generation. Running slower, closely spaced trains could maximize capacity while reducing strain on period machinery.