After his victory at the Battle of Dunbar Oliver Cromwell went on to occupy large parts of southern Scotland. David Leslie, commanding the royalist forces, in recovering from the disaster at Dunbar, created a series of defensive redoubts in the centre of the country, effectively preventing the New Model Army from making any further progress in the campaign. Unable to push past Leslie, firmly entrenched at Stirling, Cromwell was quick to realise that Fife, on the northern shore of the Firth of Forth, was now the key of the whole campaign. Once across the Forth the English would be able to march on Perth and cut the Scots lines of communication with their northern hinterland, now essential for both supplies and recruits.