The Glorious Revolution of 1688 had been swift and bloodless in England, but its consequences were anything but settled. James II fled to France, where Louis XIV -- motivated by both Catholic solidarity and the strategic advantage of keeping William III occupied -- gave him money, soldiers, and ships. James landed at Kinsale in March 1689 with 100 French officers and about 2,500 troops, then travelled to Dublin with his Lord Deputy, the Earl of Tyrconnell. But Ireland was not yet his. Protestant strongholds in the north refused to submit, and James urgently needed more supplies and equipment from France. English Parliamentarians, acutely aware of the danger, ordered the Royal Navy to intercept any French resupply.

Herbert's fleet had been at sea since early April, prowling off the Cork coast. He had left behind several ships whose crews had mutinied over unpaid wages -- an inauspicious start. The French sailed from Brest on 6 May with 24 warships, two frigates, fireships, and transports packed with arms for James's campaign. When the two fleets met off Bantry Bay, Chateaurenault had the advantage in numbers and position. The battle that followed was fierce but inconclusive. Herbert's ships took considerable damage, but his fleet was not destroyed. More importantly from the French perspective, the transports had already unloaded their cargo for James before the fighting began. The French had accomplished their primary mission -- the supplies were ashore.

Both sides claimed success. Chateaurenault withdrew to Brest on 18 May, seizing seven Dutch merchant vessels on the way home. Herbert limped to the Scilly Isles and then to Spithead via Plymouth, arriving on 22 May. William III, rather than punishing Herbert for his inconclusive showing, knighted two of his captains -- John Ashby, who had led the van, and Cloudesley Shovell -- and ordered a gratuity of ten shillings per head for the seamen. The king understood that keeping the fleet intact mattered more than winning a single engagement. The real contest would be fought over months, across the Irish Sea and on Irish soil.

With his French supplies secured, James began the Siege of Derry, hoping to crack open communications with Jacobite forces in Scotland. Three French frigates under Captain Duquesne were assigned to support him, and they proved effective -- in July, Duquesne captured two small Scottish cruisers, the Pelican and the Janet, in the North Channel. But the Allies were building strength. By summer, the Anglo-Dutch fleet in the Channel comprised 34 English and 20 Dutch ships of the line. They patrolled south of Kinsale to block further French shipments. Admiral Rooke relieved the siege of Derry on 10 August. Marshal Schomberg landed near Carrickfergus on 23 August with English reinforcements that brought the Williamite army opposing James to some 40,000 troops. The Battle of Bantry Bay had been the opening move in a campaign that would culminate the following year at the Boyne.