Battle of Rain The Battle of Rain ( also called the Battle of the River Lech or Battle of Lech ) was fought on April 15 , 1632 , as part of the Thirty Years ' War . The forces involved in this conflict were 40 , 000 Swedish troops under Gustavus Adolphus and 25 , 000 Catholic League troops under Count Johan Tzerclaes of Tilly . It was the second meeting between the two legendary generals ( see First Breitenfeld when Tilly received the first setback of his long and storied career ) and like at Breitenfeld , Tilly lost when Gustavus forced the River Lech under the cover of his superb artillery , and as there , Tilly was wounded several times and fell during the battle and was carried from the field by his men , ( who called him " Father Tilly " ) , — only this time , he would not recover from his wounds . Pontoon bridge . Gustavus had a bridge of boats constructed across the Lech river near the city of Rain through the night prior to the battle , and in the morning sent three hundred Finnish Hackapelite troops across the river under fire . The Hackapelites dug earthworks for batteries which then protected the rest of Gustavas ' army as they crossed the river . As soon as his army had crossed the river , Gustavus immediately and successfully stormed the hill . Tilly was shot in the leg early in the battle and was moved to the rear ; his second in command , Johann von Aldringen , was knocked unconscious with a skull fracture minutes later . Maximilian I , Elector of Bavaria , ordered an immediate retreat to save the now leaderless army , leaving most of the Catholic League ' s baggage and artillery in the field . The army itself may only have escaped destruction due to a storm and high winds blocking roads in the night that followed . The immediate result of the battle was that Bavaria lay open for occupation by the Swedish army , enabling Gustavus Adolphus to temporarily threaten the Austrian heartland . Tactics . The battle is , however , more interesting from a tactical point of view rather than from its outcome , as the elaborate plan of Gustavus Adolphus to catch the entire Imperial army by complex maneuvering was prevented when Tilly was mortally wounded in the battle , resulting in the early retreat of the Imperial army . The Swedish battle plan consisted of two major elements : 1 . A strong feint attack by a portion of the Swedish infantry with heavy artillery support against Tilly ' s strongly fortified center behind the river Lech . The intended effect was to attract the full attention of the Imperial army and its reserve . The Swedish force succeeded in establishing and fortifying its position on a small island or peninsula close to the Imperial side of the river . From this position , it was able to repel a series of fierce Imperial counterattacks despite being outnumbered . 2 . As the Imperial army got tied up in desperate attempts to eliminate the Swedish bridgehead , the Swedish cavalry with no opposition or attention from the enemy was able to cross the river 10 km south of the Imperial left wing . From this position they intended to outflank the entire Imperial army and thus catch it in a position with the river and the Swedish infantry at its front and the Swedish cavalry in its rear and on its flanks . With Tilly mortally wounded , the morale of the Imperial army quickly dissolved and the army withdrew before the arrival of the Swedish cavalry . Thus , Tilly ' s death possibly saved his army from annihilation . Nonetheless , both armies suffered considerable losses ( 3 , 000 on the Imperial side , 2 , 000 on the Swedish ) , mostly due to frontal attacks and counterattacks against fortified positions with strong natural defenses . The battle of Lech proves more than the Battle of Breitenfeld the innovation of Gustavus Adolphus ' tactical imagination . His daring frontal attack in combination with the deployment of a large part of his army for the flanking movement has similarities with the tactics of John Churchill , Duke of Marlborough at the Blenheim battlefield , ( situated in the very neighborhood of Rain ) or of Frederick the Great at Leuthen . The disciple of Gustavus Adolphus , Johan Banér , also employed a similar battle plan four years later in the battle of Wittstock . References . 2 . Friedrich Schiller 2012 [ 1806 ] History of the Thirty Years ' War in Germany ( Kessinger : Whitefish Monanta ) pp . 239 – 242