William de Leybourne

Admiral Sir William de Leybourne
Born1242 (1242)
DiedMarch 18, 1310(1310-03-18) (aged 67–68)
Preston, near Wingham, Kent.
Allegiance England
Branch Royal Navy
Service years1265–1306
RankAdmiral
CommandsAdmiral of the English Seas
Admiral of the South
Admiral of the West
Admiral of the Irish Sea
ConflictsBattle off Bruges
Siege of Bayonne
Siege of Caerlaverock
Siege of Winchelsea

Admiral Sir William de Leybourne (French: Guillaume de Leybourne; Latin: Willelmus de Leyburnia or Leyburna; c. 1242–1310) was an English knight and military commander, sometimes reckoned the first admiral of the English navy.