No9 Stationary Hospital 1914

My granddad Thomas Edwin Hill was one of the first soldiers to go to France, 21st August 1914, but according to his pay book, he spent some time at the No9 Stationary Hospital. I have been searching the internet and found some facts about the hospital. No9 stationary hospital would have been one of many hospitals, which were usually located near to the respective army groups. It does say 2 stationary hospitals per Army division, 400 casualties in each. No9 Stationary Hospital was located at St Nazaire from September 1914 to Le Harve from October 1914 to November 1914. Granddad Hill stated he was at the hospital, but I can not find out why. Was he injured or stationed at the unit.