Which famous composer went mad and tried to drown himself?

Robert Schumann (1810-1856). He tried to drown himself in the River Rhine, and ended his life in a lunatic asylum.

https://en.wikipedia.org/wiki/Robert_Schumann#Final_illness_and_death

Robert Schumann.

He not only jumped off the bridge and tried to drown himself in the Rhine. But even after he was rescued, and put on a boat, he again jumped off the boat and had to be pulled back. But he did call attention to himself when he started to cross that bridge so he alerted the toll-keepers to the situation, in other words, he was not like one of these people who really set it up in such a way that he would definitely die.

He composed the variations and then tried to drown himself in the Rhein river. That led him to asylum where he died, he was not allowed to compose anymore.

http://www.johnctibbetts.com/World%20of%20Robert%20Schumann/assets/intvw_ostwald.htm

Several days before his attempted suicide, Robert Schumann told his wife he needed to be committed to an asylum, for fear that if could not he might do something terrible to himself. As she was making the necessary preparations, in a moment of weakness, he managed to slip out of the house and attempt to take his own life.

The cause of Schumann's death two years later was starvation - his faculties had become so degenerated that he could no longer feed himself. Whether he decided to starve himself to death, or thought that the voices in his head were forcing him to, is still a mystery.

Other famous composers went insane (Donizetti and Smetena, for instance. And Friedrich Nietche had even tried his hand at composing). But Schumann's insanity is probably the best known case in musical history.

Tchaikovski also tried to drown himself.

http://www.azopera.com/learn.php?subcat=composerbios&composer=Tchaikovsky

The Austrian composer, Hugo Wolf, also went insane and tried to drown himself.

Wolf's last concert appearance, which included his early champion Jäger, was in February 1897. Shortly thereafter Wolf slipped into syphilitic insanity, with only occasional spells of wellbeing. He left sixty pages of an unfinished opera, Manuel Venegas, in 1897, in a desperate attempt to finish before he lost his mind completely; after mid-1899 he could make no music at all, and once tried to drown himself, after which he was placed in a Vienna asylum at his own insistence.

https://en.wikipedia.org/wiki/Hugo_Wolf

It seems Hector Berlioz, the famous French composer, suffered from moments of insanity, if not full-blown madness.

Miss Smithson went to London in 1829, and slanderous stories about her drove Berlioz insane, so that, according to legend, he wandered for two days, without food, without sleep, in desolate fields outside of Paris.

http://music.yodelout.com/hector-berlioz-1803-1869/

He also tried to drown himself at one point : http://www.hberlioz.com/Italy/index.htm