Grand Duke Nicholas Nikolaevich of Russia ( 1831 – 1891 ) Grand Duke Nicholas Nikolaevich of Russia ( ) ( 27 July 1831 in Tsarskoye Selo – 13 April 1891 in Alupka ) was the third son and sixth child of Tsar Nicholas I of Russia and Alexandra Feodorovna . He may also be referred to as Nicholas Nicolaievich the Elder to tell him apart from his son . Trained for the military , as a Field Marshal he commanded the Russian army of the Danube in the Russo - Turkish War , 1877 – 1878 . Military career . Grand Duke Nicholas Nikolaevich was born on 27 July 1831 in Tsarskoye Selo . His father arranged for Nicholas Nikolaevich a career in the army . On the day he was born , he was appointed honorary colonel in the Life Guard Lancers and enlisted into the Life Guard Sappers battalion . A soldier most of his life , he first saw active service in the Crimea War , when he was in his early twenties , taking part in the battle of Inkerman ( 1854 ) . Grand Duke Nicholas Nicolaievich showed a special interest in military engineering . In 1856 , he was appointed as general Inspector of engineers and in 1864 , he became commander of the Imperial Guard . In 1873 , he accompanied his brother , Alexander II , to Berlin at the meeting of the three emperors : Russia , Germany and Austria . The epitome of his career was the Russo - Turkish War , 1877 – 1878 , when Nicholas Nicolaievich was appointed Commander - in - Chief of the Russian armies of the Danube , although his reputation as a strategist was very low . The Grand Duke had no particular distinction in early successes in the conflict and these were followed by terrible reverses of the armies under his orders . After the expulsion of the Russian troops from Rumelia and unsuccessful attacks at Plevna , Nicholas Nicolaievich was removed from actual command , although in theory he remained in his post . The victory of his subordinates allowed him to participate in the success at Adrianople and the Treaty of San Stefano , but after the war ended , he was criticized for not seizing Constantinople when his headquarters were already established in Adrianople . The Grand Duke also suffered the acute embarrassment of being charged with financial irregularities , of receiving bribes and embezzling money from the government . His brother , Alexander II promoted Nicholas Nicolaievich ' s career and named him Commander of the St Petersburg military region . Eventually he received the ranks of Field Marshal - General , Inspector General of Cavalry and Inspector General of the Russian engineering forces . Nicholas Nicholaievich was an influential military figure ; he also served on the State Council . A Russian Grand Duke . Tall , strong and with a long thin nose , Nicholas Nicolaievich was neither handsome nor very intelligent . An incredible womanizer , Nicholas “ loved all women except for his wife ” as a contemporary wrote . He enjoyed army life , hunting and was a well - known gourmet . He was also an expert on cattle , purebred dogs , horse breeding , fishing and hunting . In his luxurious residence in St Petersburg , the Nikolayevsky Palace , built between 1853 – 1861 , horses were a favorite topic of conversation . The Grand Duke Nicholas Nicolaievich took great interest in managing his estates , but he failed to inspire affection , even in those closest to him . Marriage . Nicholas Nicolaievich unwillingly married his second cousin Grand Duchess Alexandra Petrovna , formerly Princess Alexandra of Oldenburg ( 1838 – 1900 ) , whose paternal grandmother was a daughter of Emperor Paul I . The wedding took place in St Petersburg on 6 February 1856 . Alexandra was plain and unsophisticated and the couple soon found out that they had little in common . They had two children : The marriage was in trouble from the start and four years later , Nicholas developed a permanent relationship with Catherine Chislova , a dancer from the Krasnoye Selo Theater . Their affair was quite open and they had five children : The Grand Duke arranged a change of class into the gentry for his mistress and the couple ’ s illegitimate children took the surname Nikolayev . Tsar Alexander II ignored his brother ' s affair but advised him to be discreet . Last years . Nicholas Nicolaievich was in Cannes with his two sons when his brother Alexander II was assassinated , returning immediately to Russia in March 1881 . The ascension to the Russian throne of his nephew , Alexander III , marked the beginning of the Grand Duke ' s steady decline . Alexander III did not have any special sympathy for his uncle and Nicholas Nicholaievich was resolutely deprived of all his influence . His authority suffered even further when he was involved in fraudulent military requisitions . When the Grand Duke tried to explain his actions to the Nouvelle Revue of Paris 1880 , he indiscreetly attacked government officials and military commanders and eventually was removed from his post . Alexander III also criticized his uncle ' s extramarital affairs . By then , Nicholas Nicholaievich was living openly with his mistress . His wife left him for good in 1881 and moved to Kiev , but the Grand Duchess refused to grant the divorce he would have wanted . The couple ' s adult sons took their mother ’ s side in the family break up , but continued to live at the palace and confronted Catherine once she was waiting for their father in the Palace he shared with his wife . Catherine Chislova nagged Nicholas to provide for her and their children , he soon became financially embarrassed and had to mortgage Nicholas Palace in St . Petersburg . In 1882 , Nicholas Nicolaievich was put under supervision due to the squandering of his fortune ; he lived as a private gentleman in a modest house . Grand Duke Nicholas Nicolaievich , unable to get a divorce , hoped to survive his wife and then marry his mistress , but it was Catherine Chislova who died unexpectedly in Crimea while Grand Duchess Alexandra Petrovna would survive him by nine years . Shortly after his mistress ' death , Nicholas went mad ; he had oral cancer that spread to his brain . Suffering from delusion , he was convinced that all women were in love with him . During one ballet performance , the Grand Duke even attacked a young male dancer that he took to be a woman . In 1890 , Nicholas Nicolaievich was declared insane and kept locked indoors in Crimea . He died in Alupka , Crimea on 13 / 25 April 1891 . The Grand Duke ' s reputation at the imperial court was low and his death was not deeply felt . He had squandered all his tremendous wealth and his palace was immediately sold to cancel his massive debts .