Sussex was of strategic and industrial importance to both sides during the war due to the cannon foundries and ironworks making up the Wealden iron industry in the High Weald, controlling which would have given a logistical advantage to the side that controlled them, and also because the Sussex coastline was one of the shortest routes to France – potentially a source of smuggled arms, gunpowder, troops, and bullion, as well as other equipment and materials required to wage and win a civil war.

[4] The proximity to France also meant the county could be used as an escape route by the King – another factor which made Sussex "a region that Parliament needed to keep under firm control".

Ford offered his majesty "a thousand men, and to undertake the conquest of Sussex, though sixty miles in length" and began to raise forces accordingly.

[7][8] On arriving at the western outskirts of Haywards Heath, Ford and his army were met by resistance in the form of a much smaller but more disciplined Parliamentarian force led by Colonel Herbert Morley, which was waiting for them on Muster Green.

A recorded Parliamentarian perspective of the battle survives, likely being from the "news" that reached London on 8 December of Morley's victory at Haywards Heath:[4][9] The fight was performed with their muskets at first, and after some volleys our horse broke into their van, our footmen just at that instant charging courageously into their quarters.

[9]The Parliamentarians fought with "great fierceness" in bloody hand-to-hand combat inflicting heavy casualties on the less disciplined Royalists; Morley then sent his reserves up to exploit this and completed the rout of Ford's army.

The fighting lasted for roughly an hour and resulted in at least 200 Royalists killed, wounded, or captured, while the figure for the Parliamentarian casualties is unknown.

Concurrently, the defeated Ford "conveyed himself away and left his men in the lurch to shift for themselves",[2] then Ford in the company of Thanet, his officers, and their cavalry "flying with all speed up to the not distant downs, and so to Wissum ("Wissum" being a misspelling of Wiston) to the Earl's house",[9] ("the Earl's house" being Wiston House which was later occupied by Royalist forces and then by Parliamentarian forces)[12] and then from there back to the previously captured city of Chichester,[4][5][9] where they, among others, were later besieged that December during a siege by the Parliamentarians under Sir William Waller and taken prisoner after the Royalist resistance surrendered on 27 December 1642.

[9][13] It is hypothesised by historian Philip Pavey, based on a local oral tradition his father had heard, that a group of routed Royalist stragglers retreated in a north easterly direction while being pursued by Parliamentarians and ended up 6 miles (9.7 km) north east of Muster Green in West Hoathly.

What happened to these Royalists inside St Margaret's Church if they were ever there is not known, however the impact marks on the door suggests that the Royalists were unwilling to immediately surrender, but the lack of greater documentation surrounding this event also suggests they eventually would have without further violence, probably being given quarter as was the custom at the time and thus sparing a massacre in the church.