Opposite Cologne, on the Rhine, the Protestants, in the days of bitter persecution, had established the town of Mulheim.  Several of the neighboring Protestant princes defended with their arms the refugees who settled there from all parts of Germany.  The town was strongly fortified, and here the Protestants, with arms in their hands, maintained perfect freedom of religious worship.  The city grew rapidly and became one of the most important fortresses upon the river.  The Catholics, jealous of its growing power, appealed to the emperor.  He issued a decree ordering the Protestants to demolish every fortification of the place within thirty days; and to put up no more buildings whatever.

These decrees were both enforced by the aid of a Spanish army of thirty thousand men, which, having executed the ban, descended the river and captured several others of the most important of the Protestant towns.  Of course all Germany was in a ferment.  Everywhere was heard the clashing of arms, and every thing indicated the immediate outburst of civil war.  Matthias was in great perplexity, and his health rapidly failed beneath the burden of care and sorrow.  All the thoughts of Matthias were now turned to the retaining of the triple crown of Bohemia, Hungary and the empire, in the family.  Matthias was old, sick and childless.  Maximilian, his next brother, was fifty-nine years of age and unmarried.  The next brother, Albert, was fifty-eight, and without children.  Neither of the brothers could consequently receive the crowns with any hope of retaining them in the family.  Matthias turned to his cousin Ferdinand, head of the Styrian branch of the family, as the nearest relative who was likely to continue the succession.  In accordance with the custom which had grown up, Matthias wished to nominate his successor, and have him recognized and crowned before his death, so that immediately upon his death the new sovereign, already crowned, could enter upon the government without any interregnum.

The brothers, appreciating the importance of retaining the crown in the family, and conscious that all the united influence they then possessed was essential to securing that result, assented to the plan, and cooeperated in the nomination of Ferdinand.  All the arts of diplomatic intrigue were called into requisition to attain these important ends.  The Bohemian crown was now electoral; and it was necessary to persuade the electors to choose Ferdinand, one of the most intolerant Catholics who ever swayed a scepter.  The crown of Hungary was nominally hereditary.  But the turbulent nobles, ever armed, and strong in their fortresses, would accept no monarch whom they did not approve.  To secure also the electoral vote for Emperor of Germany, while parties were so divided and so bitterly hostile to each other, required the most adroit application of bribes and menaces.

Matthias made his first movement in Bohemia.  Having adopted previous measures to gain the support of the principal nobles, he summoned a diet at Prague, which he attended in person, accompanied by Ferdinand.  In a brief speech he thus addressed them.