Such a state of precarious make-believe could not last much longer.  The Austrians were anxious that the English force in the Netherlands, which had been reinforced and was known as the Pragmatic Army, should advance into Bavaria to co-operate with the Imperial forces.  Accordingly the army, commanded by George II in person, advanced across the Main to Dettingen.  Here the king, shut in by French forces and cut off from his supplies, was rescued from a very difficult position by the valour of his troops, who on June 27, 1743 attacked and completely routed their opponents.  The States-General had already, on June 22, recognised their responsibilities; and by a majority vote it was determined that a force of 20,000 men under the command of Count Maurice of Nassau-Ouwerkerk should join the Pragmatic Army.

The fiction that the Maritime Powers were not at war with France was kept up until the spring of 1744, when the French king in alliance with Spain declared war on England.  One of the projects of the war party at Versailles was the despatch of a powerful expedition to invade England and restore the Stewarts.  As soon as news of the preparations reached England, a demand was at once made, in accordance with treaty, for naval aid from the States.  Twenty ships were asked for, but only eight were in a condition to sail; and the admiral in command, Grave, was 73 years of age and had been for fifteen years in retirement.  What an object lesson of the utter decay of the Dutch naval power!  Fortunately a storm dispersed the French fleet, and the services of the auxiliary squadron were not required.

The news that Marshal Maurice de Saxe was about to invade the Austrian Netherlands with a French army of 80,000 men came like a shock upon the peace party in the States.  The memory of 1672 filled them with terror.  The pretence of neutrality could no longer be maintained.  The choice lay between peace at any price or war with all its risks; and it was doubtful which of the two alternatives was the worse.  Was there indeed any choice?  It did not seem so, when De Fenelon, who had represented France at the Hague for nineteen years, came to take leave of the States-General on his appointment to a command in the invading army (April 26).  But a last effort was made.  An envoy-extraordinary, the Count of Wassenaer-Twickel, was sent to Paris, but found that the king was already with his army encamped between Lille and Tournay.  Wassenaer was amused with negotiations for awhile, but there was no pause in the rapid advance of Marshal Saxe.  The barrier fortresses, whose defences had been neglected, fell rapidly one after another.  All west Flanders was overrun.  The allied forces, gathered at Oudenarde, were at first too weak to offer resistance, and were divided in counsels.  Gradually reinforcements came in, but still the Pragmatic army remained inactive and was only saved from inevitable defeat by the invasion of Alsace by the Imperialists.  Marshal Saxe was compelled to despatch a considerable part of the invading army to meet this attack on the eastern frontier, and to act on the defensive in Flanders.  Menin, Courtrai, Ypres, Knocke and other places remained, however, in French hands.