Short answers, pulled from the story.
The transition from Classical to Romantic music describes the shift in European art music from the clarity and structural regularity of the Classical era to the lyrical melodies, chromaticism, and emotional expression of the Romantic era. Classical music ran from around 1750 to 1820; Romantic music ran from around 1800 to 1910.
The transition from Classical to Romantic music had multiple causes: the proto-Romantic movement Sturm und Drang, a political reaction against despotism and Enlightenment ideals, and the Industrial Revolution's expansion of orchestras and instruments. Writers including Heinrich Heine and Victor Hugo also shaped the movement by creating new lyric poetry defending liberty, fraternity, and equality.
Key figures in the transition from Classical to Romantic music include Wolfgang Amadeus Mozart, Ludwig van Beethoven, and Franz Schubert. Beethoven's Eroica and Pastoral symphonies made programmatic music central to the era; Schubert's more than 600 art songs marked him as both the last Classical composer and the first Romantic. Frederic Chopin and Franz Liszt later consolidated the movement through virtuoso piano styles.
Sturm und Drang, meaning "storm and stress," was a proto-Romantic movement that emerged in the 1760s. Johann Wolfgang von Goethe was one of its central figures. The movement challenged Enlightenment ideals through emotional intensity and individual expression, and composers such as Haydn absorbed its aesthetic, producing works like the Farewell Symphony No. 45 in F Minor.
The Industrial Revolution drove a dramatic expansion in orchestra size during the transition from Classical to Romantic music. Improvements to the piano, including cast-iron frames that enabled thicker strings and deeper, more brilliant tones, were central to the change. New instruments such as the ophicleide were introduced, while the piccolo and English horn were refined.
Franz Schubert is recognized as both the last Classical composer and the first Romantic. His earlier instrumental pieces were considered Classical, while his more than 600 art songs, melodic and harmonic in character, placed him at the beginning of the Romantic tradition. His dual classification captures how gradually the transition from Classical to Romantic music unfolded.