About a mile to the east of Langport the Wagg Rhyne is a small stream lying in a valley running north to south, draining at its southern end into the river Parrett. The Wagg Drove runs alongside the Rhyne connecting the parallel roads from Langport to Somerton at its northern end and to Pibsbury and Long Sutton at its southern end. At the Pibsbury end of the Drove the ground slopes gently to either side of the Rhyne, but towards the centre and Somerton road the rising ground overlooks the Wagg on both sides. The Wagg Rhyne though narrow, was deep with no bridge but a ford, referred to in contemporary accounts as a ‘pass’, where a narrow hedged lane crossed the Rhyne. In addition to the hedges, marshy ground along both sides of the Rhyne prevented a cavalry approach except by the pass.
The royalists took up position on the rising ground, known as Ham Hill, to the west of the Wagg. They then deployed musketeers to line the hedges leading to and from the pass. The parliamentarians took up position on the rising ground on the east side of the valley, facing the royalists across the Wagg. Goring had hoped to hold the pass until nightfall and slip away to Bridgwater under cover of darkness. The parliamentarians had no intention of allowing him to do so. Fairfax began by bombarding the royalist positions on the hill with artillery. The two royalist artillery pieces were soon silenced. The parliamentarian infantry, closely followed by their cavalry, attacked the pass. The force of the attack and lack of support from royalist reserves held in the rear, who were suffering from the heavy artillery fire, soon saw the royalists driven from the pass. Once the parliamentarian cavalry were across, a feat made difficult by the width of the pass which could only accommodate four horses abreast, the first troop charged the royalist ranks. Second and third charges were made as more cavalry gained the west bank of the Wagg. After a fierce engagement the royalists were unable to hold and a gradual withdrawal quickly became a disordered rout.
The royalist infantry fled back through the town to cross the bridge over the Parret and take the safer western route towards Bridgwater, destroying the bridge to hamper the parliamentarian pursuit. The royalist cavalry in contrast took the more direct route on the east side of the Parrett, towards Aller. Here, in Aller Drove where the road was narrow as it struck out across Sedgemoor, a detachment of cavalry halted in an attempt to fight off the pursuing parliamentarians to give Goring's other troops time to retreat back to Bridgwater.