Here however it again made an easy stand against the Protestant attacks, and at the close of February the Queen was driven to make a formal treaty with the Lords by which she promised to assist them in the expulsion of the strangers. The treaty was a bold defiance of the power from whom Elizabeth had been glad to buy peace only a year before, even by the sacrifice of Calais. But the Queen had little fear of a counter-blow from France. The Reformation was fighting for her on the one side of the sea as on the other. From the outset of her reign the rapid growth of the Huguenots in France had been threatening a strife between the old religion and the new. It was to gird himself for such a struggle that Henry the Second concluded the treaty of Cateau-Cambresis; and though Henry's projects were foiled by his death, the Duke of Guise, who ruled his successor, Francis the Second, pressed on yet more bitterly the work of persecution. It was believed that he had sworn to exterminate "those of the religion." But the Huguenots were in no mood to bear extermination. Their Protestantism, like that of the Scots, was the Protestantism of Calvin. As they grew in numbers, their churches formed themselves on the model of Geneva, and furnished in their synods and assemblies a political as well as a religious organization; while the doctrine of resistance even to kings, if kings showed themselves enemies to God, found ready hearers, whether among the turbulent French _noblesse_, or among the traders of the towns who were stirred to new dreams of constitutional freedom. Theories of liberty or of resistance to the crown were as abhorrent to Elizabeth as to the Guises, but again necessity swept her into the current of Calvinism. She was forced to seize on the religious disaffection of France as a check on the dreams of aggression which Francis and Mary had shown in assuming the style of English Sovereigns. The English ambassador, Throckmorton, fed the alarms of the Huguenots and pressed them to take up arms. It is probable that the Huguenot plot which broke out in the March of 1560 in an attempt to surprise the French Court at Amboise was known beforehand by Cecil; and, though the conspiracy was ruthlessly suppressed, the Queen drew fresh courage from a sense that the Guises had henceforth work for their troops at home. [Sidenote: Treaty of Edinburgh.]