When Catholic League forces under General Tilly approached Baden in 1622 (Palatinate campaign), he marched against them, but came too late for the Battle of Mingolsheim.

George Frederick learned the Latin, French and Italian languages and received his higher education in Strasbourg, where his brother James had studied earlier.

However, the testament had not been properly signed and sealed, and the remaining guardians held that this meant that they could allow the brothers to divide the Margraviate.

George Frederick retained the southern parts of Baden-Durlach, the Lordships of Rötteln and Badenweiler and the County of Sausenburg.

[7] Shortly after he took office in Upper Baden, George Frederick introduced Johann Weininger as the new General Superintendent at the Synod of Rötteln.

[8][9] In 1601, he promised the citizens of Pforzheim, who resisted the appointment of Reformed clergy by his brother Ernest Frederick, that he would support them when the case came before the Reichskammergericht.

He initiated a wide ranging set of legal, administrative, and religious reforms He established the Privy Council, which he presided himself.

George Frederick was aware that he could achieve his goal of a united Lutheran margraviate of Baden only with the support of the people.

[citation needed] George Frederick saw the deteriorating situation in the empire, and in his own principality in particular, and studied not only theology, but also military themes.

He reacted with an armed intervention in the Bohemian Revolt, a conflict that formed the initial phase of the Thirty Years' War.

On 19 August 1612, George Frederick concluded a defensive alliance with the Protestant cities of Bern and Zurich, with which he wanted to protect Upper Baden, as it was enclosed by territories belonging to Further Austria.

[17] The bishop of Speyer, Philipp Christoph von Sötern, felt threatened by the surrounding Protestant powers and in 1615, he began expanding his residence in Udenheim into a fortress.

He changed the name Udenheim into Philippsburg and began constructing Philipsburg Fortress, despite protests by the imperial city of Speyer, the Electorate of the Palatinate and the Margraviate of Baden.

From March to June 1620 George Frederick blocked the road from Breisach to Freiburg by order of the Protestant Union, operating from a fortified camp at Ihringen.

The goal was to prevent the passage of mercenary troops of Bavaria and the Catholic League from the Alsace to their assembly points at Lauingen and Dillingen on the Danube.

In order not to lose his Margraviate to an imperial ban for waging war on the emperor, he abdicated in 1622, in favour of his son, Frederick V. In the spring of 1622, after the Estates granted him a special war tax for three years,[19] he had between 11000 and 12000[20] mercenaries at his disposal, with a relatively large amount of artillery, in addition to the regiment that would remain behind to defend Baden.

However, he arrived too late to participate in the Battle of Mingolsheim on 27 April, where the Palatinate commander Count Ernst von Mansfeld crushingly defeated Lieutenant General Tilly of the Catholic League.

On 27 April, George Frederick declared war on the Habsburgs and combined his forces with those of Mansfeld, so as to fight the Catholic League together.

In 1625, George Frederick retreated to Geneva, where he soon came into conflict with the Calvinist government, because he held Lutheran church services in his apartment.

[21] In the summer of 1627 he was appointed lieutenant general of the Danish army by King Christian IV of Denmark, who was involved in the Danish-Lower Saxon War and tasked George Frederick with stopping the advance of Wallenstein into northern Germany.