A parade and service was held at Blandford Camp where thousands of sailors from the Collingwood Battalion trained.
The Princess Royal attended the ceremony at the battalion's memorial.
The service commemorated those who died during the Third Battle of Krithia on the Turkish peninsula.
The battalion were almost totally destroyed during the eight-month campaign that was fought from 25 April 1915 to 9 January 1916.
More than 100,000 troops were killed and hundreds of thousands more were wounded.
The centenary of the Gallipoli campaign - one of the bloodiest of World War One - has been marked with a memorial in Dorset.