Cui was the son of a French officer who remained in the Russian Empire after the war of 1812 and married a Lithuanian woman.  He spent his early years in Vilnius.  As a child Cui briefly took lessons with Moniuszko, but was generally self-taught as a musician.  He studied at the Saint Petersburg Academy of Military Engineering.  Upon graduating with high honors, he was invited back as a lecturer and later a full professor.  Cui bore a title of engineer-general, was an acknowledged expert in the area of military fortifications and authored several books on the subject.  In 1857 Cui became acquainted with Balakirev who acted as his mentor, especially in the field of orchestration.  Through Balakirev, Cui met other members of the group that was later christened the Mighty Five.  He was especially influenced by Alexander Dargomyzhsky, a veteran Russian composer admired by the group.  Cui later married Maria Bamberg, one of Dargomyzhsky’s students.  An orchestral scherzo dedicated to her was performed by the Imperial Music Society in 1859 and was considered Cui’s debut as a composer.  In 1869 he was present during the last months of Dargomyzhsky’s life and witnessed the dying composer’s attempts at finishing the Stone Guest.  According to Dargomyzhsky’s will, Cui completed the composition.  Cui began composing his most famous work, the opera William Ratcliff in 1861.  The opera was produced in Saint Petersburg 1869 and received mostly negative reviews.  It was revived thirty years later but never stayed in the repertoire.  Cui is important as a critic and music historian.  For almost forty years he contributed to music periodicals in Russia and Western Europe.  After his near retirement from music criticism in 1900 he devoted himself entirely to composing.  To that later period belong dozens of romances and numerous works for the stage including four children’s operas.