At midnight on 28 July, the English set alight eight fire ships, sacrificing regular warships by filling them with pitch, brimstone, gunpowder and tar, and cast them downwind among the closely anchored vessels of the Armada. The Spanish feared that these uncommonly large fireships were "hellburners", specialised fire ships filled with large gunpowder charges that had been used to deadly effect at the Siege of Antwerp. Two were intercepted and towed away, but the remainder bore down on the fleet. Medina Sidonia's flagship and the principal warships held their positions, but the rest of the fleet cut their anchor cables and scattered in confusion. No Spanish ships were burnt, but the crescent formation had been broken, and the fleet found itself too far leeward of Calais in the rising southwesterly wind to recover its position. The English closed in for battle.