Their initial destinations were base hospitals. Good pieces on the subject herehttps://www.historyanswers.co.uk/history-of-war/somme-2016-the-ambulance-trains-of-world-war-1-meant-the-difference-between-life-and-death/ and https://www.qaranc.co.uk/ambulancetrains.phpI imagine their would have been some sorting out at the base hospitals of those who could be treated there and those who were onward evacuated to England.MaxD