On the outbreak of the Civil War, Robartes, now firmly established as his county's
leading Parliamentarian actively sought a command in Parliaments' Army and Lanhydrock
Robartes' own Regiment of Foot was raised as one of the twenty original regiments
which made up the army under the command of the Earl of Essex. Robartes' Regiment
left London on 7th September 1642 to head for the midlands. Following an army review
at Coventry and the taking of Worcester, the army followed the King's army towards
London and on 23rd October 1642 the armies met in the wars first major engagement
at Edgehill in Warwickshire. Of eleven foot regiments present in Parliaments' army
at the battle, four fled, but the other seven, which included Robartes', were said
to have fought valiantly and helped stabilise the army when defeat looked imminent
and manage to hold out for an inconclusive outcome.
On 12th November, Robartes' Regiment along with Hampden's foot advanced to assist
the hard pressed defenders of Brentford, just outside London, but as they arrived
the parliamentary supply barge on the Thames was blown up and they fell back, leaving
the Royalists to take the town.
In December 1642, with the royalist cause in the ascendancy in Cornwall under Lord
Hopton, the royalists raided across the Tamar into Devon cutting off Plymouth's water
supply. The town's committee, now thoroughly alarmed for their safety, gave Lord
Robartes command of the town and ordered the recruitment of troops to defend themselves.
Plymouth successfully resisted these early royalist attempts at its capture, as indeed,
it would continue to do throughout the war.
In the early months of 1643 Robartes' Regiment were part of the army which, now badly
depleted due to an outbreak of typhus, was laying siege to Reading. A muster role
taken in February 1643 shows the regiment as containing 456 private soldiers.
In September of 1643 the regiment were part of the force sent to the bloodless relief
of Gloucester, although they saw some minor
action at Stow-on-the-Wold on their way. on 20th September the army met the royalists
in battle at Newbury, which despite some savage fighting ended in a stalemate. Lord
Robartes himself commanded a brigade at Newbury with some bravery. His brigade managed
to push Vavasour's foot back despite looking in danger for a while themselves. Late
1643 saw the army abandon Reading for Windsor for re-supplying and some fighting
at Olney near Newport Pagnell.