Sir John Byron was escorting a Royalist convoy of valuables from Oxford to King Charles's army in Shrewsbury and, worried about the proximity of the Parliamentarians, took refuge in Worcester on 16 September to await reinforcements.

The Parliamentarian army arrived in the city the next day and remained for four weeks before shadowing the Royalist move towards London, which led to the Battle of Edgehill.

In response Charles granted commissions of array to his commanders, a medieval device for levying soldiers which had not been used for almost a century until the King reintroduced it during the Bishops' Wars (1639–1640).

The first open conflict between the two sides occurred at Kingston-upon-Hull, where a large arsenal housed arms and equipment collected for the earlier Bishops' Wars.

[5] Charles was successful in raising men to the Royalist cause in the north of England, the East Midlands and Wales, but without control of a significant arsenal, he lacked the means to arm them.

[7] The two sides continued to recruit; Parliament positioned its main field army, commanded by the Earl of Essex, between the King and London, in Northampton.

[9][10][11] Despite this, Essex did not press his advantage: possibly because his orders allowed him to present the King with a petition to peacefully submit to Parliament, as an alternative to military action.

[13] On 13 September Charles moved his army west through Derby and Stafford towards Shrewsbury, where he hoped to be reinforced by the Royalist regiments being raised in Wales and the north-west and south-west of England.

[14] Sir John Byron was a strong supporter of King Charles and raised what was probably the first Royalist cavalry regiment of the war.

Byron's regiment left with a large convoy of gold and silver plate donated by Oxford University to help fund the King's war preparations.

[15] The Parliamentarians did not react to the movement of the Royalist army until 19 September, as they sought intelligence on the King's destination, and then moved on a parallel path through Coventry and towards Worcester.

The Parliamentarians used manoeuvres originated in the army of the Dutch Republic which was the pre-eminent force in the early 17th century, and with whom many English cavalry officers had first experienced battle.

Deploying in shallower formations than the Parliamentarians to allow a greater frontage, the Royalist cavalry attacked at the charge,[b] using their firearms only when they were already among their opponents and often relied on their swords instead.

[28] Modern historians vary slightly in their account of the first stage of the engagement: Brooks, Chris Scott, and Alan Turton have the Royalist dragoons already prepared, lining the hedges of the lane.

When the Parliamentarians advanced up the path, the dragoons opened fire on them, causing Sandys's men to panic and bolt forward into Wick Field; the musket-fire alerting the resting Royalist cavalry of their approach.

[16][29] Peter Gaunt and Trevor Royle describe all the Royalists as within the field; the noise of the Parliamentarian horsemen alerted Rupert to their approach, allowing him to quickly prepare his men for battle as best as he could.

[16] The Royalists claimed to have lost no one of note, though many of their officers, including Prince Maurice (Rupert's younger brother) and Henry Wilmot, were wounded.

[35] The historian Austin Woolrych describes Powick Bridge as having "significance ... disproportionate to its scale": it proved that the Royalists had forces capable of standing up to and beating those of Parliament, and affected the morale of both armies leading up to the Battle of Edgehill a month later.

[36] No longer threatened by the Parliamentarians, the convoy was able to continue on its journey to the King and Rupert abandoned the indefensible Worcester and returned north to Shropshire.