Initially supported by England, the Franco-Dutch War began in May 1672; French troops quickly overran much of the Netherlands, but by July the Dutch position had stabilised. Success encouraged Louis to make excessive demands, while concern at French advances brought the Dutch support from Brandenburg-Prussia, Emperor Leopold, and Charles II of Spain. In August 1673, an Imperial army entered the Rhineland; facing war on multiple fronts, the French abandoned most of their Dutch gains to focus elsewhere, retaining only Grave and Maastricht. In January 1674, Denmark joined the anti-French coalition, while in February England left the war via the Treaty of Westminster.