The invasion of the territory of the Grande Monarque accordingly took place, and was supported by a powerful English squadron, which, as Eugene's army advanced into Provence by the Col di Tende, kept the sea-coast in a constant state of alarm. No resistance, as Marlborough had predicted, was attempted; and the Allies, almost without firing a shot, arrived at the heights of Vilate, in the neighbourhood of Toulon, on the 27th July. Had Eugene been aware of the real condition of the defences, and the insubordination which prevailed in the garrison, he might, without difficulty, have made himself master of this important fortress. But from ignorance of these propitious circumstances, he deemed it necessary to commence operations against it in form; and the time occupied in the necessary preparations for a siege proved fatal to the enterprise. The French made extraordinary efforts to bring troops to the menaced point; and, amongst other reinforcements, thirteen battalions and nine squadrons were detached from Vendôme's army in the Netherlands. No sooner did Marlborough hear of this detachment, than he concentrated his forces, and made a forward movement to bring Vendôme to battle, to which the Dutch deputies had at length consented; but that general, after some skilful marches and countermarches, retired to an intrenched camp under the guns of Lille, of such strength as to bid defiance to every attack for the remainder of the campaign. Meanwhile the troops, converging towards Toulon, having formed a respectable array in his rear, Eugene was under the necessity of raising the siege, and he retired, as he had entered the country, by the Col di Tende, having first embarked his heavy artillery and stores on board the English fleet. But though the expedition thus failed in its ostensible object, it fully succeeded in its real one, which was to effect a diversion in the south of France, and relieve the pressure on the Spanish peninsula, by giving the armies of Louis employment in the defence of their own territory.
Marlborough led his army into winter quarters in the end of October, and Vendôme did the same; the weather being so thoroughly broken as to render it impossible to keep the field. He repaired first to Frankfort, where he met the Elector of Hanover, and then to the Hague, where he exerted himself to inspire a better feeling in the Dutch government, and to get Eugene appointed to the supreme command in Spain: a project which afforded the only feasible prospect of retrieving affairs in the Peninsula, and which, if adopted, might have changed the fate and ultimate issue of the war. Neither the Emperor nor the court of Madrid, however, would consent to this arrangement; the former, because he feared to lose that great general in Italy, the latter because they feared to gain him in Spain. Marlborough, meanwhile, embarked for England on the 7th November, where his presence had now become indispensably necessary to arrest the progress of court and parliamentary intrigues, which threatened to prove immediately fatal to his influence and ascendancy.