Battle of Oldendorf
The Battle of Oldendorf (German: Schlacht bei Hessisch-Oldendorf ) on 8 July 1633  was fought as part of the Thirty Years' War between the Swedish Empire and the Holy Roman Empire near Hessisch-Oldendorf, Lower Saxony, Germany. The result was a decisive victory for the Swedish Army.
The Landgrave of Hesse-Kassel, William V, as a Protestant ally of Sweden had campaigned in Westphalia, Ruhr area and the Sauerland, successfully reducing the imperial presence there. The imperial defense of the Weser area in 1633 was led by Jobst Maximilian von Gronsfeld.
On 8 July, the Swedish army commanded by George, Duke of Brunswick-Lüneburg and Marshal Dodo zu Innhausen und Knyphausen faced an Imperial relief army commanded by Field Marshal Jobst Maximilian von Gronsfeld, Count John (Johann, Jean) of Merode and Lothar Dietrich Freiherr von Bönninghausen. Merode commanded 4,450 infantrymen and 1,245 cavalry troops, Bonninghausen 4,475 infantry and 2,060 cavalry, Gronsfeld 2,000 infantry and 600 cavalry. The armies met near Hessisch-Oldendorf, northwest of Hameln.
Both armies attacked, a rare event in the Thirty Years' War, which besides Oldendorf only occurred in the Second Battle of Breitenfeld.[nb 1] The left wing of the Swedish forces was commanded by the general of Landgraviate of Hesse-Kassel and later imperial field marshal Count Peter Eppelmann Melander von Holzapfel. Subsequently, field marshal Torsten Stålhandske led a Swedish brigade. Field marshal Gottfried von Geelen participated later in the battle on the imperial side.
The Swedish victory in Oldendorf and the subsequent victory in the Battle of Pfaffenhofen on 11 August balanced their defeat in the Battle of Steinau on 10 October. Overall, Swedish and Imperial forces were "on even terms" in 1633. This only changed in the following year. While the Swedish forces won the Battle of Liegnitz on 8 May and the Battle of Landshut on 22 July, their defeat in the Battle of Nördlingen on 6 September 1634 brought about a change in the balance of power. 
Melander, the Swedish commander at Oldendorf, intrigued with the Holy Roman Emperor in 1635 to merge Hesse-Kassel's forces into the Imperial army and have Hesse-Kassel sign the Peace of Prague. These plans failed, and personal quarrels led him to leave service and to re-enter it as the Imperial commander of Westphalia in 1645. The Peace of Prague reconciled many Protestant states with the Holy Roman Emperor, most notably the Electorate of Saxony. As a consequence, Sweden's and Hesse-Kassel's forces stood alone against a growing anti-Swedish, pro-Habsburg coalition in 1635 - a disequilibrium eventually stirring France's intervention in the Thirty Years' War.
In 1647, Hessisch-Oldendorf became the winter quarters of the Swedish army commanded by Carl Gustaf Wrangel retreating from Bohemia, followed by the then imperial commander Melander who took his quarters in Hesse.
- Usually, one of the armies (the less numerous one), would take on a defensive position, while the other army (the more numerous one), would attack if its leader, having evaluated the defense of the opponent, found an attack promising. Guthrie (2003), p.121.
- Schattkowsky (2003), p.241
- Guthrie (2003), p.28
- Jaques (2007), p.448
- Guthrie (2003), p.238
- Bedürftig (2006), p.73
- Guthrie (2002), p.252
- Guthrie (2003), p.121
- Guthrie (2003), pp.237-238
- Guthrie (2003), pp.46-47
- Guthrie (2003), p.201
- Guthrie (2003), pp.238-239
- Burschel (1994), p.272
- Guthrie (2003), p.29
- Guthrie (2003), p.234
- Bedürftig, Friedemann (2006). Der Dreissigjährige Krieg: Ein Lexikon (in German). Primus. ISBN 3-89678-287-8.
- Burschel, Peter (1994). Söldner im Nordwestdeutschland des 16. und 17. Jahrhunderts (in German). Vandenhoeck & Ruprecht. ISBN 3-525-35650-1.
- Guthrie, William P (2002). Battles of the Thirty Years War: from White Mountain to Nordlingen, 1618-1635. Greenwood Publishing Group. ISBN 0-313-32028-4. Retrieved 2009-08-30.
- Guthrie, William P (2003). The later Thirty Years War: from the Battle of Wittstock to the Treaty of Westphalia. Greenwood Publishing Group. ISBN 0-313-32408-5.
- Jaques, Tony (2007). Dictionary of Battles and Sieges: F-O. Volume 2 of Dictionary of Battles and Sieges: A Guide to 8,500 Battles from Antiquity Through the Twenty-first Century. Greenwood Publishing Group. ISBN 0-313-33538-9.
- Schattkowsky, Martina (2003). Witwenschaft in der frühen Neuzeit: Fürstliche und adlige Witwen zwischen Fremd- und Selbstbestimmung (in German). Leipziger Universitätsverlag. ISBN 3-936522-79-0.