Joseph Haydn (1732 - 1809) had a gift for melody, so he was sent to Vienna to sing with the famed Vienna Boys' Choir. After expulsion for cutting the pig tails from a fellow chorister's wig, Haydn taught himself composition.
He spent roughly 30 years as court composer for the Esterhazy royal family at their remote estate in Hungary. By his own account, isolation from the world – and an unhappy wife who used his compositions for fish wrappers – “forced [him] to become original.”
Haydn's music circulated around Europe and he enjoyed widespread fame for much of his career. Such was his respect that, while invading Vienna, Napoleon posted two guards outside Haydn's home to protect him.
Much of classicism's progress was only possible because of Haydn's innovations. Known as The Father of the Symphony, the symphony and the piano sonata – two of classicism's most important forms – owe their advancements to him.
Haydn is the least-performed member of the First Viennese School, but he deserves more exposure. My father (a composer) and I listen to and discuss one or two symphonies each week. We have surprised ourselves with our newfound enthusiasm for Haydn.
“Papa” Haydn is generally acknowledged as the main influence on the era, but Mozart and Beethoven have the name recognition among even the most casual classical music listeners. I encourage everyone to listen to more Haydn (perhaps, start with the finale of his last symphony) and experience his impressive range of creativity.