Ironside visits the Maginot line

Contemporary illustration of a Maginot Line fort

The British Chief of the Imperial General Staff, Sir Edmund Ironside, meets his French opposite number, Gamelin, and inspects part of the Maginot line.

I put it to Gamelin that the great difficulty in this coming war 
would be the assembling of a great army ready to assault. The 
Siegfried and Maginot Lines are at most places fourteen miles 
apart. Each side has troops pushed out some seven miles in front 
of their main line. Patrols move about long distances into the out
post line of the other. With the “air” alert, no preparations could 
be made for a surprise. It would be a matter of months and steady 
siegework to bring up guns for bombardment. Nothing could 
be done in secret. An enormous system of trenches would inevitably grow up in front of each of the main lines and we should get 
back to the old trench warfare with an immensely strong main 
line behind.

The actual fort we saw was a marvel of engineering. It con
tained some five hundred men under an Infantry Captain. It provided about a battery of gunfire and a company of Infantry fire with anti-tank guns. It had all kinds of packed ammunition underground and could best be described as an anchored man o’ war. 
Gas-proof, and with immense power of resistance, it still seemed 
to me vulnerable in misty weather, where no observation could 
be obtained. It had to have its front defence well in front of it. Its 
cost seemed to me excessive for the security and the fire it offered. 
I think Gamelin agreed with me, though he wouldn’t say so 

See Time Unguarded: Ironside Diaries

Italian Newsreel footage of the Maginot line: