The Battle of the Boyne in 1690
The situation on the morning of July 1st, 1690, was clear - William III wanted to get through to Dublin and had to find a way across the Boyne. Easier said than done, with Drogheda occupied and fortified by Jacobite troops a crossing near the Oldbridge Estate looked the only achievable goal. So William marched his assorted troops there.
Waiting to meet him was the army loyal to James II, led by the man himself. And this is the first reason why the battle achieved fame: It was the only time both kings were actually on a battlefield, facing each other (albeit at a distance).
The battle itself, though bloody enough, was not a massive engagement. Many troops only "fought" outside musket range, others got (literally) bogged down, reduced to glaring at an enemy scowling back across a piece of unpassable land. And while the Jacobites had (in theory) a very defensible position the Williamites more than straightened the odds by having and employing artillery as well as fielding experienced soldiers. Within a few hours these soldiers, despite losing the Duke of Schomberg, managed to force a passage across the Boyne, to beat back counter-attacks and to establish a safe passage across the river, onwards to Dublin.
And here further iconic status was gained - William of Orange crossing the Boyne became the emblematic image it still is today. And James fleeing pell-mell southwards, finally to France and never to return, is not forgotten either. Neither is his remark to Lady Tyrconnel that her countrymen certainly ran well. In reply to which she observed that he seemed to have outrun them.
But one has to add that James was not too far off the mark - especially the "Gaelic Irish" regiments again proved their tendency to simply go home when their commanding officer was killed. The "cause" was a very nebulous concept to them.
The Subsequent Failure of the Jacobite Cause
As the Battle of the Boyne was not decisive in any way, the war continued. Mainly thanks to William's biggest blunder - instead of opting for peace and reconciliation he lambasted the Jacobites and drew up punitive terms under which their surrender might be recognized. Winning hearts and minds obviously was not very high on his agenda - and thus he actually managed to stiffen the enemy's resistance. Which only ended more than a year later at Limerick.
Jacobites made two more serious attempts to regain the throne for the Stuarts - in 1715 and again in 1745, the last under the ineffective but very romantic "Bonnie Prince Charlie". After the massacre of his troops during the Battle of Culloden (Scotland) the Jacobite cause effectively ran out of steam. But Culloden became as iconic for Scotland as the Battle of the Boyne is for Ireland.
The Battle of the Boyne as a Protestant Icon
Despite its ultimate historic insignificance, the Battle of the Boyne became a Protestant and Unionist icon - this was mainly due to the presence of both kings on the battlefield. The image of James running from the victorious William was too good to resist. Even if the Protestant William fought the Catholic James with the unlikely backing of Pope Innocent XI!
The Orange Order, founded in the 1790s to preserve the Protestant Ascendency, made the celebration of the battle the central event of its calendar. Which it still is today - though the highlight of the marching season is actually taking place on July 12th, the wrong day. July 12th is a public holiday in Northern Ireland and massive parades are held in commemoration of William's victory. An impressive event, though highly divisive and sectarian in character.
And a tour of (Protestant) Belfast will surely bring you face to face with the iconic image burned into Irish minds - "King Billy" in a red coat, astride a white horse, pointing his sword towards victory and a glorious Protestant-dominated future. This representation may not be historically correct, but every Irish schoolboy will instantly recognize it. On both parts of the divide. It represents not only Protestant victory but also the close connection to England.