The Casualty Returns records the total losses of vessels worldwide within incremental periods. Initially published quarterly and then annually, the Casualty Returns refer to the losses of ocean-going vessels over 100 gross tonnes. As of 1980 the Casualty Returns have been computerised.
Early issues of the Quarterly Returns provide separate and combined figures for steamers and sailing vessels, by flag and cause of loss, and for the total tonnage owned in each country. Additional lists of vessels are arranged by cause of loss with details of name, tonnage, nationality, voyage, cargo and both the date and circumstances of their loss. From 1928, editions show years of build, and from 1939, ship type.
From 1891 Annual Summaries of the returns were first published. Since 1984, the Casualty Returns have only been published annually.
During the First and Second World Wars both the Quarterly and Annual Returns were continuously published. After March 1915, details collected of war losses were limited from the published returns. At the outbreak of the Second World War, details of losses were limited only to name, tonnage and flag.
Between 1940 and 1977 the handwritten Wreck Books that were kept offer more detailed information regarding total losses and casualties.
Editions of the Casualty Returns from 1967 onwards include analyses by size, principal type and age. Later editions from 1970 onwards feature world maps displaying the approximated positions of vessels foundered, burnt, wrecked or lost as a result of collision. Details of vessels that could not be published in the quarterly returns were also included in the annual editions.
From 1950 onwards an index of all ships listed in the Casualty Returns for each year is available for consultation.
For the purposes of researching specific ships, an estimated date of loss is required in order to locate an entry. In many instances, information on ship loss may be obtained with the aid of the Register of Ships .