The French invasion of the Spanish Netherlands marked the end of the long-standing Franco-Dutch alliance, and was the first of Louis XIV's wars of expansion that dominated Western Europe for the last decades of the 17th century.

As part of the 1659 Treaty of the Pyrenees that ended the Franco-Spanish War, Louis XIV of France married Maria Theresa, eldest daughter of Philip IV of Spain.

[4] To prevent its acquisition by France, Maria Theresa renounced her inheritance rights; in return, Louis was promised a dowry of 500,000 gold écus, a huge sum that was never paid.

[8] As required by the 1662 Franco-Dutch Treaty of Paris, France entered the Second Anglo-Dutch War in July 1665, providing an excuse for its military build up; Louis also calculated that this would make it harder for the Dutch to oppose him.

[10] French lawyers argued that as the dowry remained unpaid, Maria Theresa's renunciation was invalid, and her rights "devolved" to Louis under the Jus Devolutionis, an obscure law restricting inheritance to children from a first marriage.

On this basis, he claimed most of the Spanish Netherlands, including Brabant and Limburg, the towns of Cambrai, Antwerp and Mechelen, Upper Guelders, the counties of Namur, Artois and Hainaut, and related possessions.

[11] Leopold and Mariana dismissed this claim, as the law applied only in Brabant, Namur and Hainault and concerned private property, not feudal rights; however, this gave Louis a legal justification for his actions.

[12] Aware of French intentions, Mariana's government sought to end the Portuguese Restoration War, agree to an alliance with England, and break the Franco-Dutch relationship.

Until the advent of railways in the 19th century, goods and supplies were largely transported by water; campaigns in this theatre focused on control of strongpoints along rivers such as the Lys, Sambre and Meuse.

Another 9,000 under Antoine d'Aumont prepared to advance up the Lys, via Kortrijk and Oudenaarde; de Créquy and 6,000 light cavalry were based at Sierck-les-Bains, securing their flank against an attack from Germany.

Capturing towns was relatively easy, holding them far harder, since every garrison weakened the field army; over the next century, the French confronted this strategic dilemma time and again in this theatre.

[23] The garrison were allowed to withdraw after surrendering on 28 August; three days later, de Marchin and a Spanish relief force of 12,000 ran into a French cavalry detachment on the Bruges road.

[24] On 12 September, Turenne captured Aalst but although his troops suffered relatively few battle casualties, sickness was a far bigger problem; in early October, campaigning ended for the winter.

[26] This was driven by the States of Zeeland, supported by Sir William Temple, English ambassador in the Hague and Brussels, and Francois-Paul de Lisola, Leopold's representative in London.

Finally, it allowed Charles of England to keep Parliament happy, while demonstrating Dutch unreliability and thus increasing the price Louis would pay for his support in the 1670 Treaty of Dover.

[35] To fund the 1668 campaign, Castelo Rodrigo agreed to a loan of 2 million guilders from the Amsterdam financial markets; as security, the Dutch would be allowed to occupy Bruges, Ostend and Damme.

[36] On 20 January, Louis and Leopold signed a Partition Treaty, agreeing to the division of the Spanish Empire if Charles of Spain died; this included the terms given to De Witt in September.

[38] It contained a pact of mutual defence, an agreement to ensure Spain accepted French terms, and secret clauses, including military action against France if Louis reneged on this promise.

[40] Writing ten years later, largely to justify the subsequent Franco-Dutch War, Louis claimed it was a calculated insult by the 'ungrateful Dutch nation', but his reaction at the time was far more moderate.

Franche-Comté was considered part of Burgundy, his family's traditional power base and his selection demonstrated royal control over an area with a long history as an independent state.

Possession of towns like Charleroi and Tournai facilitated future campaigns through the control of vital routes into the Spanish Netherlands, but they were easily isolated and required expensive garrisons.