The Edict of Restitution was Ferdinandís attempt to restore the religious and territorial settlement after the Peace of Augsburg (1555). The "Ecclesiastical Reservation" forbade the secularisation of Catholic land (i.e. being converted to some form of Protestant belief) after 1555. However, during the decades of weak emperors, princes had secularised Catholic land simply because it was so valuable and they had got away with it as no emperor was powerful enough to enforce the "Ecclesiastical Reservation".
The main proposal of the "Edict of Restitution" was to ensure that the "Ecclesiastical Reservation" was enforced and it affected the secularised archbishoprics of Bremen and Magdeburg, 12 bishoprics and over 100 religious houses. The Edict resulted in a great transfer of power and property away from the Protestants to the Catholics. Thousands of Protestants had to leave where they lived and go to states that were Protestant.
The greatest impact of this was in north-east Germany. It was in this area that Ferdinand's power was at its weakest, so this move was very understandable and potentially very rewarding for him. Ferdinand appointed Imperial administrators to take over the secularised states/cities. By doing this, he was re-establishing Imperial authority to an area that had enjoyed freedom from Imperial rule for nearly 100 years. The threat was implicit to the German princes. It was a move that alarmed the French - though Ferdinand was well within his rights to do what he did.
The German princes could do nothing. They had seen the Coalition destroyed and Wallenstein had a massive army in the field - 134,000 troops - to enforce Imperial authority if required.
Ironically, Wallenstein disliked the Edict as it trespassed into the region his considered his own but he played his part for the emperor to the full. He stated that "he would teach the Electors manners. They must be dependent on the emperor, not the emperor on them." Ferdinand would have approved of such words. The response of the princes was to group behind Maximillian of Bavaria to pressurise Ferdinand into dismissing Wallenstein.
Their chance came in 1630 when Ferdinand had to call a meeting of the Electors because he wanted his son, also called Ferdinand, elected King of the Romans. Ironically, the man with so much apparent power, had to rely, by law, on the votes of the Electors to maintain his dynasty in power. The meeting was held in Regensburg. Ferdinand also hoped to persuade the Electors to approve greater Imperial involvement in the wars that were being fought in Europe.
John of Saxony and George William of Brandenburg (both Protestant) stayed away in protest at the Edict of Restitution. Those Electors present realised that they had little to gain from involvement in wars that meant little to them. However, Maximillian still asked Ferdinand for the dismissal of Wallenstein.
To win over the Electors, Ferdinand sacked Wallenstein in August 1630 though Wallenstein argued that he was allowed to resign to save face. To get dismissed the most powerful military figure in Europe was a major victory for the Electors and Regensburg must be seen as a defeat for Ferdinand. However, all of this was overshadowed by an event that had happened in July 1630 - Gustavus Adolphus had landed in Pomerania with 4,000 men. No-one knew what his intentions were, but without Wallenstein, Ferdinand had to turn to Maximillian and Tilly once again.