Donald Stewart is buried at Boulogne, which was a base for hospitals from October 1914 onwards. This suggests that he was wounded in action and transferred to Boulogne for treatment. I have (so far) been unable to track his service record, and therefore do not know the date he was wounded.
On 16 October 1914, his unit was east of Bailleul near the Belgian border in northern France.
Private DONALD STEWART
Last address in Lewis: 10 Bells Road, Stornoway
Son of Murdo and Mary Stewart, of Bayhead St., Stornaway, Lewis. Served with 1st Bn. Seaforth Highlanders in India for six years.
Service unit: 2nd Seaforth Highlanders
Service number: 9469
Date of death: 16 October 1914 at the age of 25
Killed in action in France
Interred: Boulogne Eastern Cemetery, grave III. C. 37.
Local memorial: Lewis War Memorial; Nicolson WW1 memorial, right panel
Had served 5 years with the Seaforths in India and was called up as reservist at the outbreak of war.