The Nuttall Encyclopedia
Defender of Londonderry against the army of James II., born in co. Tyrone, of English parents; was in holy orders, and by his sermons encouraged the town's-people during the siege, which lasted 105 days; he afterwards fought in command of his Derry men at the battle of the Boyne, where he lost his life.
Wood, James, ed. Entry for 'Walker, George'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/w/walker-george.html. Frederick Warne & Co Ltd. London. 1900.