The National Archives has digitised around 1.5 million pages of World War I diaries, and will be releasing them throughout 2014 as part of their centenary programme, First World War 100. The project will continue over the next 5 years.

War diaries were kept for two main reasons: to provide an accurate record of operations, and to collect information that would help make improvements in preparing the army for war. They contain a wealth of information of far greater interest than the army could ever have predicted, and provide unrivalled insight into daily events on the front line.

The first release features the war diaries of the first three cavalry and the first seven infantry divisions of the British Army in the First World War. You can search the catalogue and download pdfs of the unit diaries, which may cover a period of several years.