This is a free database provided by Library and Archives Canada of War Diaries from the Canadian military serving in World War I. These diaries are not personal diaries and rarely include information about individual soldiers.
“From the start of the First World War, Canadian Expeditionary Force (CEF) units were required to maintain a daily account of their “Actions in the Field.” This log was called a War Diary. This database contains the digitized War Diaries of CEF infantry, artillery and cavalry units, Brigade, Division and Corps commands and support units such as Railway and Forestry troops. The site also includes the War Diaries of several British units that served under Canadian command. For other British units, visit the website of the National Archives. This site does not include documents relating to the Royal Canadian Navy or Canadians in flying corps, except for two pages from June 1916 for the Royal Flying Corps. In addition, units were only required to record their “Actions in the Field.” Therefore, you will find very few Diaries for periods during which units mustered in Canada, shipped to Europe, or trained in England. These are not personal diaries. War Diaries rarely record information about individual men. This is because War Diaries were never intended to document individual service and also due to the size of the unit to which a single War Diary referred. For example, Infantry Diaries were recorded by battalions, which consisted of approximately 1,000 men. Artillery Diaries were most often kept by brigades, which numbered about 4,000 men. Command-level diaries record tactical and strategic information. Once you have identified the unit in which you are interested, War Diaries provide the most complete first-hand record of how and where that unit was deployed and the wartime experiences of its individual members. The information found in the War Diaries varies greatly, and is dependent on the ability of the junior officer responsible for writing the diary on a day-to-day basis. Because of this variation, one may find a detailed account of a battalion’s involvement in a battle, a description of training exercises, or simply a sentence describing the weather.”
These diaries are searchable by viewing images.