In the 20th century, Saxony became a free state of Germany.
As with much of modern Germany, Saxony became a battlefield of the Thirty Years' War, despite the efforts of its elector, John George I to remain neutral. This stand completely vexed Gustavus Adolphus of Sweden, who, by 1631, badly needed resources and manpower.
However, Saxony finally officially joined Sweden when Count Tilly invaded Saxony and took Leipizig. John George personally took the field at the Battle of Breitenfeld, but fled shortly after the actual battle began, taking his Saxon forces with him. Gustav's forces nonetheless carried the day.
Saxony continued its neutral stance in the years that followed. While formally part of the Confederated Principalities of Europe, it did not follow Gustavus Adolphus into the Ostend War, an action Gustavus saw as a betrayal. When the CPoE was succeeded by the United States of Europe, Saxony refused to join.
Following the death of John George in September of 1635, Saxony was brought into the USE, with Duke Ernst of Saxe-Weimar as its administrator. Succession in Saxony is likely to be muddled. Regardless of the status of John George's sons (if any are alive), the children of his daughters will still be qualified to inherit.
In late 1635-early 1636, Saxony was the only part of the USE where the term "civil war" was not a misnomer. Prior to the Battle of Ostra, Johan Banér's troops had burned villages and had generally ravaged the province except in the area of Leipzig, and was opposed by Georg Kresse's irregular army.
In mid-1636, Saxony was removed from imperial administration and made a self-governing province with its head of state, styled "Chancellor", elected under a parliamentary system. One of the conditions for this was that Gretchen Richter be a candidate, in order to resolve the situation in which she, through the Committees of Correspondence, had effectively been in authority even though Duke Ernst held formal authority. In the USE's 1636 election, the Fourth of July Party won a solid majority in the province, and Richter became the first elected Chancellor of Saxony.