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.
Question: How many is the difference in the number of Swiss mercenaries and the number in the Duke of Brittany's army?
Answer: 3000