From 9th Division history this was the Battle of the Pimple and attack on Snag trench near the Butte de Warlencourt 18th October 1916. 5th Camerons, 1st South Africans and 9th Seaforths were involved. 67 Camerons died on the 18th.
His will is in the Scottish National Archives
reference SC70/8/453/11