Rupert, the son of Frederick V, Elector of Bavaria, and a nephew of Charles I, was one of the most dashing cavalry officers in Europe.  He lost no time in carrying out his commission, and in a few days Newcastle received a letter saying that he was stabling his horses that same night at Knaresborough, and that he would be at York the following day, Rupert’s own horse being stabled that same night in the church at Boroughbridge.  The news was received with great rejoicings by the besieged garrison and the people in York, but spread dismay amongst the besiegers, who thought York was about to capitulate.  To stay in their present position was to court disaster, so they raised the siege and encamped on Hessey Moor, about six miles away, in a position which commanded the road along which Rupert was expected to travel.  But by exercise of great military skill he crossed the river at an unexpected point and entered York on the opposite side.  The Prince, as may be imagined, was received with great rejoicings; bells were rung, bonfires lighted, and guns fired, and the citizens went wild with triumphant excitement.  Difficulties arose, however, between Newcastle, who was a thoughtful and experienced commander, and Rupert, who, having relieved the city, wanted to fight the enemy at once.  As he scornfully refused advice, Newcastle retired, and went with the army as a volunteer only, Meantime there were dissensions among the Parliamentary generals, who were divided in their opinions—­the English wishing to fight, and the Scots wishing to retreat.  They were all on their way to Tadcaster, in search of a stronger position, when suddenly the vanguard of Rupert reached the rearguard of the other army at the village of Long Marston.  This division of the retreating army included their best soldiers, and was commanded by Leslie and two other brave men, Sir Thomas Fairfax and Oliver Cromwell.  Their rearguard halted, and, seeing the plain covered with pursuers, they sent word to the generals who had gone on in front, asking them to return and take possession of the dry land of the Moor, which was higher than that occupied by the Royalist army.  Oliver Cromwell had already risen in the opinion of the army by his conduct in Lincolnshire, and he was dreaded by the Royalists, for he had already shown his ability to command.  Stalwart and clumsy in frame, he had an iron constitution, and was a bold and good rider and a perfect master of the broadsword then in use.  He had also a deep knowledge of human nature, and selected his troopers almost entirely from the sons of respectable farmers and yeomen, filled with physical daring and religious convictions, while his own religious enthusiasm, and his superiority in all military virtues, gave him unbounded power as a leader: 

  What heroes from the woodland sprung
    When through the fresh awakened land
  The thrilling cry of freedom rung. 
  And to the work of warfare strung
    The Yeoman’s iron hand.