In response to the dawn movement upstream of 10,000 Williamites, King James sent 17,000 men to strengthen his left wing. This left only 6,000 men to defend the Oldbridge crossing against the 26,000 Williamites.
James's men fought bravely: seven infantry battalions engaged the Williamites hand-to-hand "...there was nothing to be seen but smoke and dust, not anything to be heard but one continued fire for nigh half-an-hour".
The four remaining Jacobite cavalry regiments then took up the attack, repeatedly charging the Williamite infantry on the slopes behind Oldbridge. The Dutch Guards fixed bayonets and resisted Jacobite squadrons, but the Huguenots took heavy casualties. Marshal Schomberg (Meinhard Schomberg's father), the senior Williamite general, was killed in the melee, as were George Walker, the defender of Derry, and La Caillemotte, and one of the Huguenot colonels.
About noon, William, with 3,500 mounted troops, crossed the river downstream at Drybridge. His advance forced the Jacobites to break off the action at Oldbridge and withdraw to oppose him at Donore.