In 1938, historian CV Wedgwood argued the 1618 to 1648 Thirty Years War and the 1568 to 1648 Dutch revolt formed part of a wider, ongoing European struggle, with the Habsburg-Bourbon conflict at its centre.

[6] This included supporting the Dutch against Spain, and financing Swedish intervention in the Empire, starting in 1630, when Gustavus Adolphus of Sweden invaded Pomerania.

[9] Concerned by the prospect of the Habsburgs making peace on favourable terms in both the Empire and the Netherlands, Louis XIII and his chief minister Richelieu decided on direct intervention.

[12] In May, Louis XIII declared war on Spain, claiming to be responding to a request for support from the Elector of Trier, whose territories were an important part of the Road and had been occupied by Spanish troops.

Outside Les Avins, they made contact with a Spanish force of around 16,000,[b] commanded by Thomas Francis, Prince of Carignano and his deputies Bucquoy and Count Feria.

Their artillery commander, Charles de La Porte, positioned his guns to provide covering fire; Châtillon and Maillé-Brézé drew up their troops in standard formation, infantry in the centre and cavalry on the wings, before launching a frontal assault.

[17] Most of the Spanish casualties occurred in this phase of the battle; estimates range from a total of 4,000,[1] to 5,000 including prisoners, among them Charles of Austria, nephew of Emperor Ferdinand and Feria.

[19] Until the advent of railways in the 19th century, water was the primary means of bulk transportation; Leuven's position on the River Dyle made its capture essential for an offensive into Brabant.