Siege of Breisach

Background

The Rhine valley was heavily contested since the beginning of the Eighty Years' War. As part of the Spanish Road, Spain used it to supply troops and goods into the Netherlands. Breisach, part of Habsburg Further Austria, was the principal fortress along the Upper Rhine and considered impregnable because of its topography. The Austrian Habsburgs held the fortress against a first siege by Swedish troops in 1633. Since 1632, France had taken control of the Duchy of Lorraine and established a presence in Alsace, by offering the cities and lordships protection against the warring Swedish and Austrian troops. Control of Breisach would allow France to maintain Alsace and gain entrance into southern Germany.

Bernard of Saxe-Weimar aspired to acquire his own territory in the Holy Roman Empire. After his defeat as Swedish commander at Nördlingen in 1634, he commanded an independent army, the former troops of the Protestant Heilbronn League. A treaty with France brought him reinforcements, pay and provisions. In 1637, he went onto the offensive against Breisach, a potential capital for his desired territory. At Rhinau, he crossed the Rhine but was soon repelled by Imperial troops.

The next year, Bernard renewed his plan, this time with more preparation. He wintered in the Prince-Bishopric of Basel. From there, he planned to strike against the so-called Forest towns (Waldstädte) Rheinfelden, Säckingen, Laufenburg and Waldshut. With them he hoped to secure the Rhine south of Breisach and interrupt supplies from Lake Constance into the fortress.