Question: Who was the leader of the group of five prominent 19th century composers that Alexander Borodin was a part of?
Context: Ballet as a music form progressed from simply a complement to dance, to a concrete compositional form that often had as much value as the dance that went along with it.  The dance form, originating in France during the 17th century, began as a theatrical dance.  It was not until the 19th century that ballet gained status as a “classical” form.  In ballet, the terms ‘classical’ and ‘romantic’ are chronologically reversed from musical usage.  Thus, the 19th century classical period in ballet coincided with the 19th century Romantic era in Music.  Ballet music composers from the 17th–19th centuries, including the likes of Jean-Baptiste Lully and Pyotr Ilyich Tchaikovsky, were predominantly in France and Russia.  Yet with the increased international notoriety seen in Tchaikovsky’s lifetime, ballet music composition and ballet in general spread across the western world. Campbellite is a mildly pejorative term referring to adherents of certain religious groups that have historic roots in the Restoration Movement, among whose most prominent 19th century leaders were Thomas and Alexander Campbell.  Members of these groups generally consider the term "Campbellite" inappropriate, saying that they are followers of Jesus, not Campbell.  They draw parallels with Martin Luther's protest of the name "Lutherans" and the "Anabaptists" protest of the name given to them by their enemies.  With specific reference to the early Restoration Movement, "[t]he terms Campbellism and Campellites were universally rejected by those to whom they were applied." In mid- to late-19th-century Russia, Pyotr Ilyich Tchaikovsky and a group of composers known as The Five had differing opinions as to whether should be composed following Western or native practices.  Tchaikovsky wanted to write professional compositions of such quality that they would stand up to Western scrutiny and thus transcend national barriers, yet remain distinctively Russian in melody, rhythm and other compositional characteristics.  The Five, made up of composers Mily Balakirev, Alexander Borodin, César Cui, Modest Mussorgsky, and Nikolai Rimsky-Korsakov, sought to produce a specifically Russian kind of art music, rather than one that imitated older European music or relied on European-style conservatory training.  While Tchaikovsky himself used folk songs in some of his works, for the most part he tried to follow Western practices of composition, especially in terms of tonality and tonal progression.  Also, unlike Tchaikovsky, none of The Five were academically trained in composition; in fact, their leader, Balakirev, considered academicism a threat to musical imagination.  Along with critic Vladimir Stasov, who supported The Five, Balakirev attacked relentlessly both the Saint Petersburg Conservatory, from which Tchaikovsky had graduated, and its founder Anton Rubinstein, orally and in print. Anatoly Andreyevich Brandukov (Russian: Анато́лий Андре́евич Брандуко́в ) (January 6 [O.S. December 25, 1858] 1859 – February 16, 1930) was a Russian cellist who premiered many cello pieces of prominent composers including Pyotr Tchaikovsky and Sergei Rachmaninoff.  Born as Russian classical music was flourishing in the middle of the 19th century, he worked with many of the important composers and musicians of the day, including performances with Anton Rubinstein and Alexander Siloti.  As a soloist, he excelled in performance and was especially noted for stylish interpretations, his refined temperament, and beautiful, expressive tone.  In his later years, he became a professor at Moscow Conservatory, and continued to perform well into his later life.  Although his popularity is obscured by the more famous composers and virtuosos, his influence on those composers' most prominent compositions is evident. Alexander Porfiryevich Borodin (Russian: Алекса́ндр Порфи́рьевич Бороди́н ; ] , 12 November 183327 February 1887) was a Russian Romantic composer of Georgian origin, as well as a doctor and chemist.  He was one of the prominent 19th century composers known as The Mighty Handful, a group dedicated to producing a uniquely Russian kind of classical music, rather than imitating earlier Western European models. The Mighty Handful (Russian: Могучая кучка ), also known as The Five and The New Russian School, were five prominent 19th-century Russian composers who worked together to create a distinctly Russian classical music.  Mily Balakirev (the leader), César Cui, Modest Mussorgsky, Nikolai Rimsky-Korsakov and Alexander Borodin all lived in Saint Petersburg, and collaborated from 1856 to 1870. Russian Easter Festival Overture: Overture on Liturgical Themes (Russian: Светлый праздник, "Svetliy prazdnik" ), Op.  36, also known as the Great Russian Easter Overture, is a concert overture written by the Russian composer Nikolai Rimsky-Korsakov between August 1887 and April 1888.  It was dedicated to the memories of Modest Mussorgsky and Alexander Borodin, two members of the group of composers known in English as "The Five".  It is the last of what many call his three most exceptionally brilliant orchestral works, preceded by "Capriccio Espagnol" and "Scheherazade".  The work received its premiere at a Russian symphony concert in St. Petersburg in late December 1888. Edgewood is a historic home located at Frederick, Frederick County, Maryland, United States.  It is a two-story multipart limestone farmhouse featuring narrow courses of native stone.  The house was constructed and added to over the 18th and 19th century and reflects the Greek Revival style popular at that time.  It is associated with the Schley family, prominent 19th century residents of Frederick County, who held the farm from 1830 until 1911. Debendra Ghosh (19th century C.E.) was a prominent 19th century Bengali writer.  He was a major figure in the Vangiya Sahitya Parishad . Mount Hooker (12509 ft ) is located in the Wind River Range in the U.S. state of Wyoming.  Mount Hooker was named for Joseph Dalton Hooker, prominent 19th century British botanist and explorer.  The north and east slopes of Mount Hooker present some of the tallest and steepest vertical cliffs in Wyoming and the peak is also remote, being more than 20 mi from a road.  The formidable 1800 ft north face of Mount Hooker was first climbed in 1964 by renowned Yosemite Valley climber Royal Robbins along with Dick McCracken and Charlie Raymond, who took over three days to scale the cliff face.  In 2013, a team free climbed one pitch rated at class 5.14a , grade VI during a multiple-day ascent requiring five other pitches rated above 5.12.
Answer: Mily Balakirev