With the accession of Mary however all was changed. Under Henry and Edward the Catholicism of Scotland had profited by the national opposition to a Protestant England; but now that Catholicism was again triumphant in England Protestantism became far less odious to the Scotch statesmen. A still greater change was wrought by the marriage with Philip. Such a match, securing as it did to England the aid of Spain in any future aggression upon Scotland, became a danger to the northern realm which not only drew her closer to France but forced her to give shelter and support to the sectaries who promised to prove a check upon Mary. Many of the exiles therefore who left England for the sake of religion found a refuge in Scotland. Amongst these was John Knox. Knox had been one of the followers of Wishart; he had acted as pastor to the Protestants who after Beaton's murder held the Castle of St. Andrews, and had been captured with them by a French force in the summer of 1547. The Frenchmen sent the heretics to the galleys; and it was as a galley slave in one of their vessels that Knox next saw his native shores. As the vessel lay tossing in the bay of St. Andrews, a comrade bade him look to the land, and asked him if he knew it. "I know it well" was the answer; "for I see the steeple of that place where God first in public opened my mouth to His glory; and I am fully persuaded, how weak that ever I now appear, I shall not depart this life till my tongue glorify His holy name in the same place!" It was long however before he could return. Released at the opening of 1549, Knox found shelter in England, where he became one of the most stirring among the preachers of the day, and was offered a bishoprick by Northumberland. Mary's accession drove him again to France. But the new policy of the Regent now opened Scotland to the English refugees, and it was as one of these that Knox returned in 1555 to his own country. Although he soon withdrew to take charge of the English congregation at Frankfort and Geneva his energy had already given a decisive impulse to the new movement. In a gathering at the house of Lord Erskine he persuaded the assembly to "refuse all society with idolatry, and bind themselves to the uttermost of their power to maintain the true preaching of the Evangile, as God should offer to their preachers an opportunity." The confederacy woke anew the jealousy of the government, and persecution revived. But some of the greatest nobles now joined the reforming cause. The Earl of Morton, the head of the house of Douglas, the Earl of Argyle, the greatest chieftain of the west, and above all a bastard son of the late king, Lord James Stuart, who bore as yet the title of prior of St. Andrews, but who was to be better known afterwards as the Earl of Murray, placed themselves at the head of the movement. The remonstrances of Knox from his exile at Geneva stirred them to interfere in behalf of the persecuted Protestants; and at the close of 1557 these nobles united with the rest of the Protestant leaders in an engagement which became memorable as the first among those Covenants which were to give shape and colour to Scotch religion.