Maximilian I, Elector of Bavaria in the context of "Catholic League (German)"

The Electorate of Bavaria (German: Kurfürstentum Bayern) was a quasi-independent hereditary electorate of the Holy Roman Empire from 1623 to 1806, when it was succeeded by the Kingdom of Bavaria.

The Wittelsbach dynasty which ruled the Duchy of Bavaria was the younger branch of the family which also ruled the Electoral Palatinate. The head of the elder branch was one of the seven prince-electors of the Holy Roman Empire according to the Golden Bull of 1356, but Bavaria was excluded from the electoral dignity. In 1621, Frederick V, Elector Palatine was put under the imperial ban for his role in the Bohemian Revolt against Ferdinand II, Holy Roman Emperor, and the electoral dignity and territory of the Upper Palatinate was conferred upon his loyal cousin, Duke Maximilian I of Bavaria. Although the Peace of Westphalia would create a new electoral title for Frederick V's son, with the exception of a brief period during the War of the Spanish Succession, Maximilian's descendants would continue to hold the original electoral dignity until the extinction of his line in 1777. At that point the two lines were joined in personal union until the end of the Holy Roman Empire. In 1805, after the Peace of Pressburg, the then-elector, Maximilian Joseph, raised himself to the dignity of King of Bavaria, and the Holy Roman Empire was abolished the following year.

Henri de La Tour d'Auvergne, vicomte de Turenne (11 September 1611 – 27 July 1675), commonly known as Turenne (French: [tyʁɛn]), was a French general and one of only six marshals to have been promoted Marshal General of France. The most illustrious member of the La Tour d'Auvergne family, his military exploits over his five-decade career earned him a reputation as one of the greatest military commanders in history.

Born to a Huguenot family, the son of a Marshal of France, he was introduced to the art of war at a young age. He first served as a volunteer in the Dutch States Army under the orders of his maternal uncles Maurice of Nassau and Frederick Henry before pursuing his career in the service of France, where his noble origins and proven qualities soon saw him rise to the top of the military hierarchy. He rose to prominence during the Thirty Years' War by capturing the fortress of Breisach in 1638. Promoted Marshal of France in 1643, he struck against Bavaria the following year, defeating the Bavarian army in three years of campaigning and forcing the Elector of Bavaria to make peace. The Elector soon broke the treaty and in 1648 Turenne invaded again with Swedish support, subduing the Imperial army at Zusmarshausen and pacifying Bavaria.

The Diet of Regensburg of 1623 was a meeting of the Imperial States of the Holy Roman Empire (or Fürstentag) convened by Holy Roman Emperor Ferdinand II. The meeting was not technically an imperial diet in the full sense, but a convention of princes or Deputationstag – a looser constitutional format giving the emperor greater leeway to make decisions without being bound by formal procedures. At the meeting, the Electorate of the Palatinate was transferred to Maximilian I of Bavaria. The meeting marked the high-water mark of imperial power during the Thirty Years' War.

The Palatine Anthology (or Anthologia Palatina), sometimes abbreviated AP, is a manuscript collection of Greek poems and epigrams discovered in 1606 in the Palatine Library in Heidelberg. It is based on the lost collection of Constantine Kephalas of the 10th century, which in turn is based on older anthologies. It contains material from the 7th century BC until 600 AD and later on was the main part of the Greek Anthology which also included the Anthology of Planudes and more material.

The manuscript of the Palatine Anthology was discovered by Saumaise (Salmasius) in 1606 in the Palatine library at Heidelberg (Codex Palatinus 23). In 1623, during the Thirty Years' War, it was sent with the rest of the Palatine Library to Rome as a present from Maximilian I of Bavaria to Pope Gregory XV and it was kept in the Vatican Library. In 1797 it was taken to Paris by order of the French Directory and in 1816 it was returned to Heidelberg when the war ended, but one (smaller) part of it remained in Paris (Parisinus Suppl. Gr. 384).

The Battle of Rain took place on 15 April 1632 near Rain in Bavaria during the Thirty Years' War. A Swedish army under Gustavus Adolphus of Sweden defeated a Catholic League force led by Johann Tserclaes, Count of Tilly, who later died of wounds received in the battle.

Outnumbered and with many inexperienced troops, Tilly built defensive works along the River Lech, centred on the town of Rain, hoping to delay Gustavus long enough for Imperial reinforcements under Albrecht von Wallenstein to reach him. The Swedes spent 14 April bombarding the defences, then crossed the river the next day, inflicting nearly 3,000 casualties, including Tilly. On 16 April, Maximilian of Bavaria ordered a retreat, abandoning his supplies and guns.