Throughout the year 1643 the advantage in arms had lain decidedly with the King, and the Parliament now sought new strength in an alliance with the Scots. Such an alliance involved a strict adherence to Presbyterianism, which was naturally very distasteful to the Independents, who were growing steadily in strength and numbers. Therefore, though the entrance of the Scots into England in January 1644, brought a valuable accession of military force, it proportionately weakened the Puritan Party by increasing its internal dissensions. For a brief period the Independents sought alliance with those members of the Parliament and of the City, known as the Peace Party, and the result of this drawing together was a resolve to appeal privately to the King for some terms of agreement. The emissary employed in this secret negotiation was a certain Ogle, who had long been held a prisoner, but was now purposely suffered to escape. As an earnest of good faith, he was to assure the King that Colonel Mozley, brother of the Governor of Aylesbury, would admit the Royalists into that town. But Ogle was himself betrayed. Mozley had communicated all to the Presbyterian leaders of the Parliament. The whole plot was carefully watched, and plans laid to entrap Rupert himself. It was said that Essex boasted that he would have the Prince in London, alive or dead. On the night of January 21st, Rupert set out to take possession of the offered town. The snow fell thick, but it did the Prince good service, for it prevented Essex falling {129} upon him, as had been intended. Fortunately, also, Rupert was prudent, and declined to approach very near Aylesbury, until Mozley should appear on the scene in person. This he failed to do. Then the Prince wished to assault the town on the side where he was not expected, but the brook which ran before it was so swelled by the snow and sudden thaw, as to be impassable. Nothing remained but a speedy retreat, in which, owing to wind, snow and swollen streams, some four hundred men perished. In his fury Rupert would have hanged Ogle for a traitor, but the unfortunate man was rescued by the intercession of Digby. Probably the Secretary was moved as much by detestation of Rupert as by compassion for Ogle. There was soon a new _causa belli_ between them.