In 1687, the diet of Ratisbonne refused to convert the twenty years' truce into a definitive peace.

By his haughty pretensions the king gave to the coalition the support of Pope Innocent XI.; Louis XIV.

was once more single-handed against all, when he invaded the electorate of Cologne in the month of August, 1686.

Philipsburg, lost by France in 1676, was recovered on the 29th of October; at the end of the campaign, the king's armies were masters of the Palatinate.

In the month of January, 1689, war was officially declared against Holland, the emperor, and the empire.
The commander-in-chief of the French forces was intrusted to the dauphin, then twenty-six years of age.