Louis was born in Thouars the eldest son of Louis I de la Trémoille. He commanded an army that attempted to secure Brittany for the French crown after internal revolts had weakened Francis II, Duke of Brittany during the so-called "Mad War" . His decisive victory at the Battle of Saint-Aubin-du-Cormier on 28 July 1488 ended effective Breton independence. He took part in several battles in the Italian Wars, notably the Battle of Fornovo  and the Battle of Agnadello . He suffered a severe defeat at the Battle of Novara, in which his 10,000-strong army was ambushed by 13,000 Swiss mercenaries. He later went on to secure a French victory at the Battle of Marignano , but he perished at the Battle of Pavia on 24 February 1525, where he died of a wound inflicted by an arquebus. His death occurred during the climax of the battle when the French were surprised by 1500 Spanish arquebusiers. La Trémoille and other high-ranking Frenchmen fought their way towards their king, Francis I, in order to protect him. La Trémoille fell from his horse, shot through the heart.. Whose decisive victory at the Battle of Saint-Aubin-du-Cormier ended effective Breton independence?