Prelude
Following the Swedish defeat at the Battle of Nördlingen in 1634, Bernhard's mercenary army had come under the pay of France. Having been pushed to the west bank of the Rhine by the Imperial advance, Bernhard's army had settled in Alsace during 1635 and had done little except help repulse the Imperial invasion of France under the Cardinal-Infante Ferdinand and Matthias Gallas in 1636.
Early in February 1638, having been prodded by the French government, Bernhard advanced his army of 6,000 men and 14 guns to the Rhine in order to find a crossing. Arriving at an important crossing point at the town of Rheinfelden, Bernhard prepared to invest the town from the south. Meanwhile, he would use the ferry at Beuggen to throw troops across the river in order to complete the investment from the north. The attack on the town was to be made on 1 March.
In order to prevent this, the Imperialists, under the Italian mercenary Count Federico Savelli and German general Johann von Werth, moved through the Black Forest to attack Bernhard's army and relieve the town.
Johann von Werth, also Jan von Werth or in French Jean de Werth, was a German general of cavalry in the Thirty Years' War.
The Battle of Nördlingen took place on 6 September 1634 during the Thirty Years' War. A combined Imperial-Spanish force inflicted a crushing defeat on the Swedish-German army.
Bernard of Saxe-Weimar was a German prince and general in the Thirty Years' War.
The Battle of Freiburg, also called the Three Day Battle, took place on 3, 5 and 9 August 1644 as part of the Thirty Years' War. It took place between the French, consisting of a 20,000 men army, under the command of Louis II de Bourbon, Duc d'Enghien, and Henri de La Tour d'Auvergne, Viscount de Turenne, and a Bavarian-Imperial army of 16,800 men under Field Marshal Franz von Mercy. On 3 and 5 August, the French suffered heavy casualties despite having greater numbers. On the 9th, Turenne's army tried to flank the Bavarians by heading to Glottertal through Betzenhausen and cut off their supplies, while Mercy moved to St. Peter where they faced off against each other. The Bavarians repelled the attack of the French vanguard and retreated while leaving behind parts of their baggage and artillery. Having resulted in heavy casualties on both sides, the French side claimed victory because of the Bavarian retreat but the battle is also often seen as a draw or a Bavarian tactical victory as the French army took much heavier casualties and failed their goal of relieving or retaking Freiburg. However, France gained a strategical advantage in the following campaign by leaving Freiburg behing and reaching the sparsely defended Upper Rhine region prior to Mercy and in consequence conquering large parts of it.
Rheinfelden is a municipality in the canton of Aargau in Switzerland, seat of the district of Rheinfelden. It is located 15 kilometres east of Basel. The name means the fields of the Rhine, as the town is located on the High Rhine. It is home to Feldschlösschen, the most popular beer in Switzerland. The city is across the river from Rheinfelden in Baden-Württemberg; the two cities were joined until Napoleon Bonaparte fixed the Germany–Switzerland border on the Rhine in 1802 and are still socially and economically tied.
The Battle of Jankau, also known as Jankov, Jankow, or Jankowitz, took place in central Bohemia, on 6 March 1645. One of the last major battles of the 1618 to 1648 Thirty Years' War, it was fought between Swedish and Imperial armies, each containing around 16,000 men. The more mobile and better led Swedes under Lennart Torstensson effectively destroyed their opponents, commanded by Melchior von Hatzfeldt. However, the devastation caused by decades of conflict meant armies now spent much of their time obtaining supplies, and the Swedes were unable to take advantage.
Franz Freiherr von Mercy, Lord of Mandre and Collenburg, was a German field marshal in the Thirty Years' War who fought for the Imperial side and was commander-in-chief of the Bavarian army from 1643 to 1645. In that role, he destroyed a French army at Tuttlingen (1643), stalemated another at Freiburg (1644), destroyed a third French army at Herbsthausen (1645) and was killed at the Second Battle of Nördlingen (1645).
The Battle of Zusmarshausen was fought on 17 May 1648 between Bavarian-Imperial forces under von Holzappel and an allied Franco-Swedish army under the command of Carl Gustaf Wrangel and Turenne in the modern Augsburg district of Bavaria, Germany. The allied force emerged victorious, and the Imperial army was only rescued from annihilation by the stubborn rearguard fighting of Raimondo Montecuccoli and his cavalry.
The Battle of Tuttlingen was fought in Tuttlingen on 24 November 1643 between the French army in Germany led by Marshal Josias Rantzau, composed of French soldiers and the so called Weimarans or Bernhardines, German troops once in service of Bernard of Saxe-Weimar. They were defeated by the forces of the Holy Roman Empire, Bavaria and Spain led by Franz von Mercy. Technically, Mercy led a military force composed of his Bavarian army, supported by Imperial, Spanish, and Lorrainer troops. The French army was wiped out in a surprise attack in heavy snowfall along with French strategic gains since 1638. The French court suppressed the defeat and it remains largely unknown today, even among historians of the war.
The Last Valley (1959), by J. B. Pick, is an historical novel about the Thirty Years' War (1618–1648). The story occurs from September 1637 to March 1638, and centres on two men – a mercenary soldier and an intellectual – who are fleeing the destruction and starvation wrought by religious war. In southern Germany, each man stumbles upon a fertile valley untouched by the war. Soldier and intellectual, man of arms and man of mind, must collaborate to preserve the peace and plenty of the last valley from the stress and strain of the religious bigotry that caused thirty years of war in Europe.
The Relief of Thionville took place on 7 June 1639, during the Thirty Years' War.
Federico Savelli was an Italian military commander who fought in the Thirty Years' War.
The Battle of Strasbourg Bridge was fought during the Swedish phase of the Thirty Years' War near the Free city of Strasbourg, in the Holy Roman Empire. Having dealt a heavy defeat on the Swedish army at the Battle of Nördlingen in September, the armies of the Emperor, Spain and the Catholic League overran much of the Swedish-held southern Germany. As a result, the Swedish commander, Rheingrave Otto Louis, decided to retreat over the Rhine with his army, using the Strasbourg bridge.
Johann von Götzen was a Lüneburg nobleman and Generalfeldmarschall who fought during the Thirty Years' War. He was married to Elisabeth of the Falke family, with whom he had two sons: Johann Sigismund, Count of Götzen (1622-1622) and Johann, Georg Count of Götzen (1623-1679).
Adrian von Enkevort was a Brabantine nobleman and Generalfeldmarschall who fought during the course of the Thirty Years' War and the Franco-Spanish War (1635–59). He followed his father's footsteps becoming an officer, his first success came in 1632 when he distinguished himself at the Battle of Lützen, receiving the rank of Oberstleutnant in the forces of the Holy Roman Empire. He was later sent to the Rhine front where he assisted Charles of Lorraine in reclaiming his lost realm. After a short spell in the Spanish invasion of Picardy, he returned to the Rhine where he was captured by the French, spending three years in captivity. Upon his return in 1641, he was promoted to Generalfeldmarschall and dispatched to Germany where he campaigned extensively. In 1648, he became the supreme commander of the Bavarian forces, serving in this capacity until the end of the war. He was subsequently ennobled and received the sum of 3,000 Goldguldens for his service during the war. He died in 1663.
Johann von Geyso was a German nobleman and General-Lieutenant, who fought during the course of the Thirty Years' War. After studying in a Dutch military academy, Geyso fought as a mercenary in the armies of Sweden, Bohemia, Denmark and the German Protestant Union. In 1628, having gained significant experience in warfare he returned to his native Hesse-Kassel which he served until the end of the Thirty Years' War, reaching the rank of commander in chief of the Langraviate's forces and becoming ennobled.
The Battle of Kempen was a battle during the Thirty Years' War in Kempen, Westphalia on 17 January 1642. It resulted in the victory of a French-Weimar-Hessian army under the French Comte de Guébriant and the Hessian Generalleutnant Kaspar Graf von Eberstein against the Imperial Army under General Guillaume de Lamboy, who was captured.
The Battle of Altenheim took place on 1 August 1675 during the 1672-1678 Franco-Dutch War near Altenheim, in modern Baden-Württemberg. It was fought by a French army of 20,000, jointly commanded by the Marquis de Vaubrun and the Comte de Lorges, and an Imperial Army of 30,000 under Raimondo Montecuccoli.
The Battle of Ortenbach, also known as the Battle of Gengenbach, took place on 23 July 1678 during the closing stages of the 1672-1678 Franco-Dutch War, in the modern German state of Baden-Württemberg. It featured a French army commanded by François de Créquy and an Imperial force under Charles V, Duke of Lorraine.
The siege of Philippsburg was a French siege of the Rhine fortress of Philippsburg during the Thirty Years' War. After the battle of Freiburg in early August, the French under the Duc d'Enghien refrained from attacking the city and marched north to besiege Philippsburg instead. The place fell after a two-week siege. The French took Worms, Oppenheim, Mainz and Landau over the following weeks.
France 
Weimar Army
Holy Roman Empire 
Bavaria 