After the battle of Towton the Lancastrians would never again have been able to shake Edward's throne, had he continued on good terms with his great supporter Warwick. It would be irrelevant to discuss the causes of the quarrel between them: it suffices to say that the breach ultimately became irreparable, and that Warwick determined to restore Henry VI. Before the vast power of the house of Neville, in alliance with the Lancastrian party, and strengthened by others whom Edward's conduct had offended, the king was helpless, and fled the country without striking a blow. For some months Warwick reigned in the name of the imbecile Henry VI.; but in March 1471 Edward was enabled by his brother-in-law, the duke of Burgundy, to land with a small force at the mouth of the Humber. He deliberately perjured himself by solemnly swearing in York Minster that he would never again claim the crown, and that he only came to claim his ancestral lands, and then marched southwards to try his luck. He conducted his enterprise with great skill and audacity, but his enemies also played completely into his hands. Northumberland, perhaps out of jealousy of the Nevilles, made no attempt to move southwards with the forces he raised in the extreme north. Montagu, Warwick's brother, who held Pontefract, apparently did not deem himself strong enough to attack Edward without Northumberland's co-operation. The earl of Oxford moved from the eastern counties upon Newark, but shrunk back in alarm when Edward turned to attack him. Somerset was far away in the south-west. Warwick was doing his best to gather an army in the midlands, and was at Coventry when Edward, who had by this time accumulated a respectable army, moved from Leicester. As he knew that Montagu was following Edward from the north, and Oxford threatening him from the east, as he was every day expecting his son-in-law the duke of Clarence to join him from the west, Warwick chose to play a cautious game, and let Edward pass Coventry without fighting. The next news that Warwick heard was that Clarence had joined Edward: without principle to keep him true to any cause, without judgment to discern his own best interest, Clarence was always ready to plunge into a new treason. Edward now deemed himself strong enough to march on London, where his cause had always been popular, and on April 11 took possession of the capital without a blow. Hearing that Warwick was approaching, he moved out on the 13th to meet him, and on that night the two armies bivouacked opposite each other north of the little town of Barnet. Warwick had been joined not only by Montagu and Oxford, but also by Somerset: Edward had drawn considerable reinforcements from Essex. Of the numbers on each side very conflicting accounts are given, but from the narrative of the battle it would seem that there was no very great disparity, though probably Warwick had some little superiority; neither side can well have had 20,000 men, possibly much less.