Meanwhile far more serious trouble was brewing in Bohemia, where the followers of Hus had blended with the disciples of Luther, and where in many centres there was a strong feeling against the Catholic Church. According to the concessions granted by Rudolph (1609), knights and free cities were at liberty to build Protestant churches, but a similar concession was not made to the subjects of Catholic lords. Regardless of or misinterpreting the terms of the concession, however, the Protestant tenants of the Archbishop of Prague and of the Abbot of Braunau built churches for their own use. The archbishop and abbot, considering themselves aggrieved, appealed to the imperial court. According to the decision of this court the church built on the lands of the archbishop was to be pulled down, and the other on the lands of the abbot was to be closed (1618). A deputation representing the Protestant party was appointed to interview the imperial representatives at Prague, and the reply to their remonstrances being regarded as unfavourable, the mob attacked the building, and hurled the councillors who were supposed to be responsible for it through the windows. Under the direction of Count Thurn and some other Protestant nobles a provisional government was established in Bohemia, arrangements were made to organise an army, and as a beginning in the work of reform the Jesuits were expelled. Owing to the strong anti-German feeling of the populace the rebellion spread rapidly in Bohemia, and Count Mansfeld hastened to the relief of the insurgents with an army placed at his disposal by the /Union/. Most of the cities of Bohemia were captured by the rebels, and the whole of northern Austria stood in the gravest danger. At this critical moment the Emperor Matthias passed away, and was succeeded by Ferdinand II. (1619-37). The latter was a devoted Catholic, trained by the Jesuits, and had already done immense service to the Church by wiping out almost every trace of heresy in his hereditary dominions. That such a man should succeed to the imperial dignity at such a time was highly distasteful to the Protestants of Bohemia. It was not, therefore, to be wondered at that they refused to acknowledge him as king, and elected in his stead Frederick V. of the Palatinate (1619).