The Aa is a small river in the Netherlands. It rises near Nederweert in the southeastern province of Limburg, in the Peel region. It flows northwest through the province of North Brabant towards 's-Hertogenbosch, roughly along the Zuid-Willemsvaart canal. In 's-Hertogenbosch, at the confluence of the Aa and the Dommel, the river Dieze is formed, which flows into the Meuse a few km further. The main cities and towns along the Aa's course are Asten, Helmond, Veghel and 's-Hertogenbosch.

The siege of 's-Hertogenbosch also known as the siege of Bois-Le-Duc was an action in 1629, during the Eighty Years' War and the Anglo–Spanish War in which a Dutch and English army captured the city of 's-Hertogenbosch. The city had been loyal to the King of Spain since 1579 and was part of the Spanish Netherlands.