Irish Mariners contains an index of nearly 25,000 Irish born merchant seamen contained in the CR10 series of index cards in the Southampton Civic Archives. The CR10 Archive holds 300,000 cards covering the multinational workforce of the British Merchant Marine during the period from early September 1918 and the end of World War 1 to December 1921. All ranks and jobs at sea are covered from master to scullion. A unique feature of the CR 10 cards is that they usually contain a good photograph of the seaman. At this time RS2 Identity books, with matching photographs were issued to the seamen.