Young Heiden fought in Caucasus and against the Hungarian Revolutionary Army, whom Nicholas I. assisted Austrian emperor against. He was promoted to colonel in 1849. During Crimean War Heiden was chief of staff in Baltic Corps, without participation in notable battles. After the war was he was promoted to Major General in 1855. He married in 1854 Countess Elisabeth Nikolayevna Zubova whose mother was Countess Alexandra Raimond-Modène. Her father Count Nikolay Dmitrievich Zubov was Steward of the Russian Imperial Court, himself son of princess Paraskeva Viazemskaia and general, count Dmitri Alexandrovich Zubov, one of brothers of prince Platon Zubov. Countess Elisabeth was a first cousin of countess Olga van Suchtelen, one of heiresses of that Finnish comital house whose males in 1860s became extinct. After the war Heiden was chiefly a member of the General Staff. He participated in Dmitry Milyutin's military reforms and was appointed as head of the General Staff in 1866. He also chaired the conscription committee that enacted the conscription in Russia in 1874, and was in charge of the mobilization during the Turkish War; he was acting Minister of War during Milyutin's absence during the Turkish War. In 1870 Heiden was promoted to full General. When he was eleven years later appointed as Governor-General of Finland, he had made a long and successful military career.
Governor-General
As it was usual with persons who adopted themselves a new nationality, Heiden was eagerly Russian. In his position in Finland, the Slavophile Heiden saw his task to Russify the country. However, his reputation among the Finns is not very bad, because of his subtle methods - his successor, general Bobrikov, enjoys a really contrasting fame of a russifying tyrant. To attain his goal Heiden supported use of Finnish as language of administration, university and military, as opposed to Swedish. In appointments to public offices in government, administration, justice, and military he favored the conservative and monarchist Finnish Party and persons who had learned the Russian language well and resided longer times there, as opposed to possibly separatist Swedes and liberal Swedish Party. Heiden furthered trade between Finland and Russia, and had customs formalities reduced. His chief interest was to clarify jurisdiction within Finland: to define what decisions belonged to the imperial government, what to autonomous local governments in Finland. He was awarded Order of Prince Danilo I and a number of other decorations.
