Battle of Aughrim The Battle of Aughrim ( ) was the decisive battle of the Williamite War in Ireland . It was fought between the Jacobites and the forces of William III on 12 July 1691 ( old style , equivalent to 22 July new style ) , near the village of Aughrim in County Galway . The battle was one of the more bloody recorded fought on Irish soil – over 7 , 000 people were killed . It meant the effective end of Jacobitism in Ireland , although the city of Limerick held out until the autumn of 1691 . The campaign . The Jacobite position in the summer of 1691 was a defensive one . In the previous year , they had retreated behind the River Shannon , which acted as an enormous moat around the province of Connacht , with strongholds at Sligo , Athlone and Limerick guarding the routes into Connacht . From this position , the Jacobites hoped to receive military aid from Louis XIV of France via the port towns and eventually be in a position to re - take the rest of Ireland . Godert de Ginkell , the Williamites ' Dutch general , had breached this line of defence by crossing the Shannon at Athlone - taking the town after a bloody siege . The Marquis de St Ruth ( General Charles Chalmont ) , the French Jacobite general , moved too slowly to save Athlone , as he had to gather his troops from their quarters and raise new ones from rapparee bands and the levies of Irish landowners . Ginkel marched through Ballinasloe , on the main road towards Limerick and Galway , before he found his way blocked by St Ruth ’ s army at Aughrim on the 12th of July 1691 . Both armies were about 20 , 000 men strong . The soldiers of St Ruth ’ s army were mostly Irish Catholic , while Ginkel ' s were English , Scottish , Danish , Dutch and French Huguenot ( members of William III ’ s League of Augsburg ) and Irish Protestants . The Jacobite position at Aughrim was quite strong . St Ruth had drawn up his infantry along the crest of a ridge known as Kilcommadan Hill . The hill was lined with small stone walls and hedgerows which marked the boundaries of farmers ' fields , but which could also be improved and then used as earthworks for the Jacobite infantry to shelter behind . The left of the position was bounded by a bog , through which there was only one causeway , overlooked by Aughrim village and a ruined castle . On the other , open , flank , St Ruth placed his best infantry under his second - in - command , the chevalier de Tessé , and most of his cavalry under Patrick Sarsfield . The battle . The battle started with Ginkel trying to assault the open flank of the Jacobite position with cavalry and infantry . This attack ground to a halt after determined Jacobite counter - attacks and the Williamites halted and dug in behind stakes driven into the ground to protect against cavalry . The French Huguenot forces committed here found themselves in low ground exposed to Jacobite fire and took a great number of casualties . Contemporaneous accounts speak of the grass being slippery with blood . To this day , this area on the south flank of the battle is known locally as the " Bloody Hollow " . In the centre , the Williamite infantry under Hugh Mackay tried a frontal assault on the Jacobite infantry on Kilcommadan Hill . The Williamite troops , mainly English and Scots , had to take each line of trenches , only to find that the Irish had fallen back and were firing at them from the next line . The Williamite infantry attempted three assaults , the first of which penetrated furthest . Eventually , the final Williamite assault was driven back with heavy losses by cavalry and pursued into the bog , where more of them were killed or drowned . In the rout , the pursuing Jacobites manage to spike a battery of Williamite guns . This left Ginkel with only one option , to try to force a way through the causeway on the Jacobite left . This should have been an impregnable position , with the attackers concentrated into a narrow lane and covered by the defenders of the castle there . However , the Irish troops there were short on ammunition . Mackay directed this fourth assault , consisting mainly of cavalry , in two groups - one along the causeway and one parallel to the south . The Jacobites stalled this attack with heavy fire from the castle , but then found that their reserve ammunition , which was British - made , would not fit into the muzzles of their French - supplied muskets . The Williamites then charged again with a reasonably fresh regiment of Anglo - Dutch cavalry under Henri de Massue . Faced with only weak musket fire , they crossed the causeway and reached Aughrim village with few casualties . A force of Jacobite cavalry under Henry Luttrell had been held in reserve to cover this flank . However , rather than counterattacking at this point , their commander ordered them to withdraw , following a route now known locally as " Luttrell ' s Pass " . Henry Luttrell was alleged to have been in the pay of the Williamites and was assassinated in Dublin after the war . The castle quickly fell and its Jacobite garrison surrendered . " [ The ] fire from the castle on the right . . . was insignificant for it slew but a few in the passage . The reason of it was given because the men had French pieces , the bore of which was small and had English ball which was too large . " The Jacobite general Marquis de St Ruth , after the third infantry rush on the Williamite position up to their cannons , appeared to believe that the battle could be won and was heard to shout , " they are running , we will chase them back to the gates of Dublin " . However , as he tried to rally his cavalry on the left to counter - attack and drive the Williamite horse back , he was decapitated by a cannon ball . At this point , the Jacobite position collapsed very quickly . Their horsemen , demoralised by the death of their commander , fled the battlefield , leaving the left flank open for the Williamites to funnel more troops into and envelope the Jacobite line . The Jacobites on the right , seeing the situation was hopeless , also began to melt away , although Sarsfield did try to organise a rearguard action . This left the Jacobite infantry on Killcommadan Hill completely exposed and surrounded . They were slaughtered by the Williamite cavalry as they tried to get away , many of them having thrown away their weapons in order to run faster . One eyewitness , George Storey , said that bodies covered the hill and looked from a distance like a flock of sheep . Aftermath . Estimates of the two armies ' losses vary . It is generally agreed that about 7 , 000 men were killed at the battle . Some recent studies put the Williamite dead as high as 3 , 000 , but they are more generally given as between 1 - 2 , 000 , with 4 , 000 Jacobites killed . However the Williamite death toll released by them at the time was only 600 and they claimed to have killed fully 7 , 000 Jacobites . Many of the Jacobite dead were officers , who were very difficult to replace . On top of that , another 4 , 000 Jacobites either deserted or were taken prisoner . What was more , they had lost the better part of their equipment and supplies . For these reasons , Aughrim was the decisive battle of the Williamite war in Ireland . The city of Galway surrendered without a fight after the battle , on advantageous terms , and the Jacobites ' main army surrendered shortly afterward at Limerick after a short siege . The battle , according to one author , " seared into Irish consciousness " , and became known in the language tradition as " Eachdhroim an áir " - " Aughrim of the slaughter " . The contemporary Gaelic poet Séamas Dall Mac Cuarta wrote of the Irish dead , " It is at Aughrim of the slaughter where they are to be found , their damp bones lying uncoffined " . Another poet wrote , " Our friends in vast numbers and languishing forms , left lifeless in the mountains and corroded by worms " . Since it marked the end of the Irish Catholic Jacobite resistance , Aughrim was the focus of Loyalist ( particularly Orange Order ) celebrations in Ireland on 12 July up until the early 19th century . Thereafter , it was superseded by the Battle of the Boyne in commemorations on " the Twelfth " due to the switch to the Gregorian calendar ( in which 1 July became 11 July and 12 July became 22 July ) . It has also been suggested that the Boyne was preferred because the Irish troops there were more easily presented as cowardly than at Aughrim , where they generally fought bravely . The Aughrim battlefield site became the subject of controversy in Ireland over plans to build the new M6 motorway through the former battlefield . Historians , environmentalists and members of the Orange Order objected to the destruction of the 1691 battlefield . The motorway opened in 2009 .