The neutralisation of Rupert's fleet and its bases, the defeat of the Irish Royalists at Rathmines and Drogheda in 1649 and of the Scots at the Battle of Dunbar in 1650 made the Commonwealth more assertive in its relations with the Dutch, both on trade and on William II's support for the Stuart cause. French support for the English Royalists had led the Commonwealth to commence the issuing of letters of marque against French ships and against French goods in neutral ships in December 1649. Dozens of neutral Dutch ships were detained near French ports by English ships operating under letters of marque, and some of these were seized. Dutch concerns were further raised by an English embargo on Dutch trade with Scotland declared soon after.