Under circumstances like these, the Duke had little political influence except in the diplomatic circle; but he found himself mixed up with all the serious continental affairs, in consequence of the important part he had formerly played; and he was present at the congress of Verona. He preserved a certain degree of influence in foreign affairs during Mr. Canning's ministry, although the Whig party was in the ascendant. Russia appeared at this time likely to become the rival of England; the Greek question caused considerable public excitement, and difficulties existed as to fixing the new boundaries of the Hellenic territory. Mr. Canning, therefore, considered it necessary a person of great consideration should be sent to St. Petersburg, and the Duke of Wellington, being held in high estimation by the Emperor Nicholas, and having also been actively engaged in most of the questions of general interest, it was decided that his mission should be attached to the treaty of the sixth of July, which established the independence of Greece, and settled her territorial boundaries. It had become necessary the business should be finally decided; and as, in England, strong prejudices against individuals are never indulged in when business is at stake, the Duke of Wellington was selected as being the person most capable of being useful.
When he returned to England Mr. Canning was dead; Lord Goderich's ministry was struggling feebly with the difficulties it had to encounter, and as diplomatic matters were assuming a singularly complicated appearance, the king thought it advisable to form a Tory ministry of men of capacity and experience. It was composed of Mr. Peel, Lord Aberdeen, and the Duke of Wellington; and peculiarly adapted for resisting any encroachments on the part of Russia. When the Duke came seriously to examine into the state of the country, he was convinced that one of the first steps necessary to secure the efficiency and consistency of his ministry was the emancipation of the Catholics. This had long been a favourite idea in his family; and Marquis Wellesley[38] had formerly detached himself from George III. on this very question. The Duke had no hesitation as to the course he was to pursue, and a bill presented to parliament was passed by a majority; the Tories were desirous of the glory of originating so just and equitable a measure.[39]