He was sent to Prague, perhaps the most God-forsaken spot in the whole empire.  Every imaginable sect had accumulated in Bohemia during the preceding twenty years.  Scarcely a vestige of Catholicism remained, and Hussites, Wicklifites, Vaudois, Lutherans, Zwinglians, and various other offshoots of the principal sects, were busy relegating each other in eloquent terms to eternal damnation, when the arrival of Catholic missionaries gave the signal for a coalition against the common enemy of them all.  At Prague itself, where Canisius was charged to found a college with the injunction not to leave Bohemia until it should be solidly established and in a flourishing condition, the Hussites outnumbered the others.  Scarcely had he arrived and set to work, when the Duke of Bavaria, reminding St. Ignatius that Canisius had only been lent to Austria, claimed him, at least temporarily, for the foundation of the college which the Society was to establish at Ingolstadt.  The claim was admitted to be just, and accordingly the affairs of Prague could only be proceeded with four months later, when Canisius returned from Germany, having been made provincial.

It was the beginning of Lent 1555, and on the 21st April twelve priests sent to him from Rome by St. Ignatius, arrived to second him in his perilous undertaking.  The first time the Jesuits appeared in the streets they were saluted with handfuls of mud cast at them by the city urchins, who had been bribed to insult them.  The cry “Dogs of Jesuits” (a play upon the word Canisius) followed them wherever they went.  Father Peter was himself assailed with a large stone hurled through the window of the church as he stood at the altar saying Mass.  A plot was formed to throw the whole community one by one into the Moldau, as they passed over the bridge that connected the old and the new town; and ruffians, who had received a part of their reward in advance, were stationed in the middle of the bridge to waylay them.  But a timely edict issued by the Archduke of Bohemia threatened with the most severe penalties whoever should raise a hand against any member of the Society, or even treat any one of them disrespectfully.  He went still further, and sent a detachment of guards to the college daily, with orders to accompany each of the priests wherever he went, and in sufficient numbers to prevent any attack.

Added to the open enmity and fierce hatred which they inspired, the Jesuits had to encounter the jealousy of the University professors, who would have been willing enough that they should preach, but who, on the opening of their college, did all they could to hamper them and prejudice people against them.