While on front-line service, Bloch contracted severe arthritis which required him to retire regularly to the thermal baths of Aix-les-Bains for treatment. He later remembered very little of the historical events he found himself in, writing only that his memories were "a discontinuous series of images, vivid in themselves, but badly arranged, like a reel of motion picture film containing some large gaps and some reversals of certain scenes". Bloch later described the war, in a detached style, as having been a "gigantic social experience, of unbelievable richness". For example, he had a habit of noting the different coloured smoke that different shells made — percussion bombs had black smoke, timed bombs were brown. He also remembered both the "friends killed at our side ... of the intoxication which had taken hold of us when we saw the enemy in flight". He also considered it to have been "four years of fighting idleness". Following the Armistice in November 1918, Bloch was demobilised on 13 March 1919.