Most six-generation charts hold at least one man who was of age in 1914, usually a great-grandparent, and his war is the part of his life best documented and least often looked up. Four records do most of the work. Start with the medal index card (The National Archives series WO 372, searchable by name on their website and on Ancestry): almost every man who served overseas has one, and it gives his regiment, service number and the campaign medals he was owed, which is the key to everything else. Second, the medal rolls themselves (WO 329, on Ancestry) often add the battalion, and with a battalion you can read the unit war diary (WO 95, Western Front diaries on The National Archives website) for what his unit was doing on any given day. Third, try for a service or pension record (WO 363 and WO 364, on Ancestry and Findmypast): most were destroyed by bombing in the Second World War, so finding one is luck, but a surviving file gives his address, next of kin, height, wounds and postings. Fourth, if he died, the Commonwealth War Graves Commission's free Find War Dead search gives the date, the cemetery or memorial, and often his parents' names and home address, which is a genealogical record in its own right.
New this month and worth knowing: Findmypast's 2 October release added two rolls of British medals awarded to foreign-born servicemen, 1914 to 1920, 7,144 and 4,235 records with nationality and rank, for the Belgian, French, Russian and other men who served under British command. On a chart, a war death is recorded the same way as any other: year and place, so 1916, Somme or 1917, Passchendaele sits in the segment where a date and a parish would otherwise go.
🔗 Guide: The National Archives: British Army soldiers of the First World War · 🔗 Free search: Commonwealth War Graves Commission: Find War Dead · 🔗 New records: Findmypast: Military Medals Awarded to Foreigners by the British Government, 1914 to 1920