The "Covenant" of the lords sounded a bold defiance to the Catholic reaction across the border. While Mary replaced the Prayer-Book by the Mass, the Scotch lords resolved that wherever their power extended the Common Prayer should be read in all churches. While hundreds were going to the stake in England the Scotch nobles boldly met the burning of their preachers by a threat of war. "They trouble our preachers," ran their bold remonstrance against the bishops in the Queen-mother's presence; "they would murder them and us! shall we suffer this any longer? No, madam, it shall not be!" and therewith every man put on his steel bonnet. The Regent was helpless for the moment and could find refuge only in fair words, words so fair that for a while the sternest of the reformers believed her to be drifting to their faith. She was in truth fettered by the need of avoiding civil strife at a time when the war of England against France made a Scotch war against England inevitable. The nobles refused indeed to cross the border, but the threat of a Scotch invasion was one of the dangers against which Mary Tudor now found herself forced to provide. Nor was the uprise of Protestantism in Scotland the only result of her policy in giving fire and strength to the new religion. Each step in the persecution had been marked by a fresh flight of preachers, merchants, and gentry across the seas. "Some fled into France, some into Flanders, and some into the high countries of the Empire." As early as 1554 we find groups of such refugees at Frankfort, Emden, Zuerich, and Strassburg. Calvin welcomed some of them at Geneva; the "lords of Berne" suffered a group to settle at Aarau; a hundred gathered round the Duchess of Suffolk at Wesel. Amongst the exiles we find many who were to be bishops and statesmen in the coming reign. Sir Francis Knollys was at Frankfort, Sir Francis Walsingham travelled in France; among the divines were the later archbishops Grindal and Sandys, and the later bishops Horne, Parkhurst, Aylmer, Jewel, and Cox. Mingled with these were men who had already played their part in Edward's reign, such as Poinet, the deprived Bishop of Winchester, Bale, the deprived Bishop of Ossory, and the preachers Lever and Knox. [Sidenote: The Extreme Protestants.]