Sometime around 9am on the 13 December, Waller’s army approached Alton from the west. Meanwhile, parliamentarian Lieutenant Colonel John Birch advanced with some of the force toward the north of the town and was able to take six royalist sentries prisoner, another though escaped and alerted Crawford to Waller’s attack.

At this point, Crawford attempted to break out westwards from Alton with his cavalry, ostensibly to collect reinforcements from Winchester. His first attempt was repulsed, but eventually 300 royalist horse escaped southwards, pursued by some of the parliamentarian horse for a short time. In the meantime, Waller’s remaining cavalry surrounded the town to prevent Colonel Bolles’ infantry from also escaping.

Next, from the north and north–west of Alton, the infantry regiments of Waller, Hazelrig and Springate advanced towards St Lawrence’s Church. Lining the hedges, they fired at royalist musketeers positioned in various buildings near the church. One brick building in particular was heavily occupied by the royalists, who fired out of every available window. This held up the parliamentarians until Waller brought up his artillery, including his new leather guns. They bombarded the buildings until the royalists were forced to evacuate and fall back towards the church.

At the same time, the London Brigade and Samuel Jones’ Greencoats had descended from the hillside to the west of Alton. Here, they faced fierce volleys from a royalist half-moon and another breastwork. These were not overcome until the Green Auxiliaries, likely advancing south of the source of the river Wey, improvised by setting fire to a thatched house to blind the royalist defenders. Together with the Yellow Auxiliaries, the Greencoats and Trained Band musketeers then drove the royalists out of the works.

By now, Bolles’ men were defending from the churchyard and a great earthwork to the north of it. After two hours, they abandoned the south-eastern corner of the churchyard due to heavy musketry from the Yellow and Westminster regiments. The great work was quickly abandoned too, as the royalist infantry, now being surrounded by parties of parliamentarian musketeers entering the churchyard, fought back ferociously.

 As brutal hand-to-hand combat ensued, some parliamentarians threw hand grenades through the church windows, whilst others led by Major William Shambrooke managed with difficulty to force open the church door. Within the church, royalist pikemen and musketeers defended from a breastwork made of dead horses. At this stage, Colonel Bolles, who had reputedly threatened to kill the first of his men to call for quarter, was killed, reportedly from being hit with the butt end of a musket. Family tradition meanwhile claims he was killed whilst standing in the church’s pulpit. After his death, some of his men fought to the end, though others surrendered.

Having only sustained minimal losses, the parliamentarians had killed 50 to 60 royalists and taken hundreds of prisoners, many of whom later changed sides. This was good news for Waller, as after the battle the London Brigade refused to continue their service, though they did lead the remaining prisoners back to London.