This fonds is composed of "The Seaforth Highlanders’ diary", which is in fact a collection of typescripts and manuscripts by Duncan W. P. Strang written during the First World War. They mainly contain a typescript draft of an unifinished book on the Seaforth Highlanders during the war, as well as abstracts of diaries and accounts of battles and tactical operations, and reflection on war and military strategy.

The first text is the most structured and the most complete. It is a typescript of the beginning of Strang’s unfinished book "The Seaforth Highlanders in The Great War", up to the sub-chapter on "The Battle of Ypres", in the second chapter. It also includes printed photographs in black-and-white, and military operation diagrams and maps. The rest of the documents are manuscript drafts of texts that are already in this typescript, as well as drafts of later chapters, and Strang’s own diaries and notes.

These texts give us a very detailed account of day-to-day military operations and actions of the Seaforth Highlanders from the point of view of an officer directly involved in the war, while the conflict was actually taking place. Strang’s writings show that he was perfectly aware of the unprecedented character of this war, which he calls "Armageddon". In the text entitled "Past and Present", he considers that this new type of modern warfare has given rise to "new valours": "the present titanic conflict has presented absolutely new heights of military gallantry and endurance to be scaled; has set up pinnacles of heroic achievement and service undreamt of by the bravest soldiers before". He then gives his motivations for writing this diary: "it is inevitable that in the light of such a novel and unprecedented situation it should be both desirable and necessary to record at the earliest possible moment the deeds and achievements of regiments under the new conditions". He adds that his "peculiar task" is "to set forth the services and achievements of the Seaforth Highlanders under the new conditions and judged by the new standards, to tell the heroic story of their splendid deeds, to show how transcending all their own unsurpassed records in the past, they have never once flinched or failed, and have achieved every aspect and phase of the new discipline and valour".

Also includes the original folders entitled "The Seaforth Highlanders" (which contained the papers), and "Seaforth highlanders. Extracts from the London Gazette. Honours awarded to the officers with records of their Deeds of Valour. 1914-1918" (empty).