As negotiations had started in 1644, war continued largely unabated. There was no comprehensive cease-fire agreement between the belligerents. To quote delegates at Munster: "We negotiate in winter and we fight in the summer."

Even ignoring the complexities of the new reality of powers in Germany, there were several obstacles to peace due to the strategic interest of external players such as France and Sweden. German states had signed the Peace of Prague in 1635, with major concessions such as the revocation of the Edict of Restitution, prohibition of alliances among states against each other, and even further amnesty to rebellious princes such that a united army of the HRE could be found to stop the invasion of France and Sweden. So in a large way, the Peace of Prague effectively put an end to the religious aspect of the 30YW.

But of course, by that point France and Sweden were already major players in Germany itself, what with the presence of their armies. France wanted a fragmented Germany and concessions in Alsace and the Rhine area. It also wanted Spain to be weakened through the wars in the Low Countries and in the Pyrenees. Sweden wanted to keep her gains in the Baltics and weak Germany. There was also the question of, how should the final status look like? There is also the issue of demobilization, as everybody had learned from the 100YW that a mob of armed men out of control was a very dangerous thing. To give an example, the army of Hesse-Kassel was still a dangerous presence in the field, even if it was a homeless army as Hesse-Kassel itself had been invaded and controlled by Bavaria!

Both the Catholic side and the Protestant sides were highly fractured. This led to a series of one-on-one peace agreements. In 1646, France and the Emperor signed a preliminary peace treaty. Devastating failures in the field forced some Catholic electors to a separate peace with Sweden in 1647, but the emperor failed to make peace with Sweden at that point. So the Swedish moved to Austria, and the French continued to threaten Bavaria. The emperor decided to support Bavaria and war broke out again, to devastating losses against the Catholic forces. Now France and Sweden both increased their demands -- including elevation of Louis XIV to princedom in the HRE -- such that peace was not possible.

So once again, a preliminary peace was negotiated, but there was no final settlement. But following this time period, the French cardinal Mazarin instructed his negotiators to conclude peace as soon as possible due to the outbreak of the Fronde rebellion in France. So, dire internal rebellion reversed France's position in the 30YW. Further, French funding became unavailable due to their inability to collect taxes. And up to that point, France had been a major source of funds for the anti-Imperial forces, including Sweden.

Sweden was the last major player unable to achieve a satisfactory peace, due to the amount of indemnity she sought. In Bavaria, Sweden alone faced the combined forces of Austria and Bavaria. So in summer 1648, Sweden, without the support of France, moved eastwards to invade Bohemia and laid siege to Prague. The intention of this, to force Imperial troops to abandon Bavaria and move east to relieve Prague.

But why Prague? They decided to not attack Austria's major cities lest they were forced to a long, difficult siege. Prague had fallen several times before with little fighting, so it offered a chance for victory in a short time, without significant losses, and of course, plunder. Swedish commander Konnigsmarck led a "flying column" and obtained a list of wealthy pro-Imperial Bohemians as targets.

They were aided by Ernest Odowalsky, a former imperial captain who had been disabled and was without pension. Odowalsky pointed to weak points on the lesser side of the city of Prague, to take half of the old town, the larger half of Prague, divided into two parts by the Moldau. Further reinforcements arrived from Sweden with fresh troops. The Swedes sacked their part of the city to great losses, while defenders desperately tried to stop them from crossing over to their side of the city. Unfortunately for the Swedes, the approach of winter at last drove the besiegers into their quarters, and time ran out as peace was finally signed.

So the Swedes besieged Prague in order to force a final settlement involving a large indemnity. Prague's imperial garrison survived because the final peace was signed -- just in the nick of time!

Schiller's The Thirty Years War.

Wilson's Europe's Tragedy.