The Action of 30 May 1781 was a naval battle fought between two frigates of the Royal Navy and two of the Dutch Republic off the Barbary Coast. In the Netherlands it is known as the zeegevecht bij Kaap Sint-Marie (sea battle of Cape St Mary, after the Cabo de Santa Maria). In a battle lasting more than two hours, Captain William Peere Williams-Freeman of the Flora (36 guns), compelled Captain Pieter Melvill's Castor (36 guns) to strike her colours. Shortly after, Captain Gerardus Oorthuys of den Briel (36 guns) compelled Thomas Pakenham to strike Crescent (28 guns). However, Flora came to Crescent rescue before Oorthuys could board her, and forced him to retreat.