Meanwhile a renewed war was declared against Louis XIV. on account of his determination to place his grandson on the throne of Spain. The Tories were bitterly opposed to this war of the Spanish succession, as unnecessary, expensive, and ruinous to the development of national industry. They were also jealous of Marlborough, whose power they feared would be augmented by the war, as the commander-in-chief of the united Dutch and English forces. And the result was indeed what they feared. His military successes were so great in this war that on his return to England he was created a duke, and soon after received unusual grants from Parliament, controlled by the Whigs, which made him the richest man in England as well as the most powerful politically. Yet even up to this time the relations between his wife and the Queen were apparently most friendly. But soon after this the haughty favorite became imprudent in the expressions she used before her royal mistress; she began to weary of the drudgeries of her office as mistress of the robes, and turned over her duties partially to a waiting-woman, who was destined ultimately to supplant her in the royal favor. The Queen was wounded to the quick by some things that the Duchess said and did, which she was supposed not to hear or see; for the Duchess was now occasionally careless as well as insolent. The Queen was forced to perceive that the Duchess disdained her feeble intellect and some of her personal habits, and was, moreover, hostile to her political opinions; and she began to long for an independence she had never truly enjoyed. But the Duchess, intoxicated with power and success, did not see the ground on which she stood; yet if she continued to rule her mistress, it was by fear rather than love.
About this period (1706) the struggles and hostilities of the Whigs and Tories were at their height. We have in these times but a feeble conception of the bitterness of the strife of these two great parties in the beginning of the eighteenth century. It divided families, and filled the land with slanders and intrigues. The leaders of both parties were equally aristocratic and equally opposed to reform; both held the people in sovereign contempt. The struggle between them was simply a struggle for place and emolument. The only real difference in their principles was that one party was secretly in favor of the exiled family and was opposed to the French war, and the other was more jealously Protestant, and was in favor of the continuance of the war. The Tories accused Marlborough of needlessly prolonging the war in order to advance his personal interests,—from which charge it would be difficult to acquit him.