Edited sentence: He was a younger brother of Ferdinand IV of Hungary and Mariana of Austria.Historian William Coxe described Leopold in the following manner: "His gait was stately, slow and deliberate; his air pensive, his address awkward, his manner uncouth, his disposition cold and phlegmatic.In 1655, he was chosen king of Hungary and, in 1656, king of Bohemia, while Leopold gained the crown of Croatia in 1657.In July 1658, more than a year after his father's death, he was elected emperor at Frankfurt in spite of the intrigues of Jules Cardinal Mazarin, who wished to place on the imperial throne Ferdinand Maria, Elector of Bavaria or some other prince whose elevation would break the Habsburg succession.Intended for the Church, he received a good education but his prospects were changed by the death of his elder brother Ferdinand IV, on July 9 1654 of smallpox, when he became his father's heir.Leopold was physically unprepossessing.Leopold's long reign covers one of the most important periods of European history; for nearly the whole of its forty-seven years he was pitted against Louis XIV of France, whose dominant personality completely overshadowed Leopold.Mazarin, however, obtained a promise from the new emperor that he would not send assistance to Spain, then at war with France, and, by joining a confederation of German princes, called the league of the Rhine, France secured a certain influence in the internal affairs of Germany.Short and sickly, he had inherited the Habsburg lip to a degree unusual even in his inbred family.The emperor was not himself a man of war, and never led his troops in person; yet the greater part of his public life was spent in arranging and directing wars.The first was with Sweden, whose king Charles X found a useful ally in the prince of Transylvania, György II Rákóczi, a rebellious vassal of the Hungarian crown