Eventually, he returned to England, but England turned out to be a very sad place for him. His mother died of a stroke before he was able to see her again; one of his best friends drowned; and his sister Augusta's marriage was almost completely wrecked. He wrote no poetry for a long time. But, at the insistence of a friend, the first two Cantos of Childe Harold were published in February 1812, and Byron became an overnight sensation. Women everywhere were throwing themselves at him, in some cases almost literally. Lady Caroline Lamb was the most noted and determined of these women. Byron got tired of her very soon after their affair started12, and in fact, soon expressed a desire to marry Caroline's cousin, Annabella Milbanke13. She turned him down and Byron consoled himself with a quick affair with Lady Oxford.
All right, now we come to the strange part. In 1813, Augusta came to visit her brother as a way of escaping her financial and personal problems, and I'm afraid there's little doubt that she and Byron had an affair at this time14. In 1814, though, Byron was right back proposing to Annabella, and this time she gave in. They were married on 2 January 1815. On 10 December 1815, Annabella gave birth to a girl, named Augusta Ada. In February 1816, Annabella asked for a formal separation, which Byron, somewhat in shock, agreed to15. London society, doubtful before, made up its mind and Byron was thoroughly snubbed everywhere he went. So in April, Hobhouse, Fletcher, and Byron set out for Europe once again, this time with Dr. John Polidori16 also along. In May, the group met Percy Shelley and Mary Godwin (later Shelley), who were shocking everyone by living in sin. They were travelling with Mary's stepsister, Clare Clairmont, who immediately threw herself at the bored and embarrassed Byron17.
Shelley and Byron hit it off extremely well. They travelled everywhere together, finally ending up in Italy, and Byron decided that this was the place for him18. While there, he finished up Childe Harold, wrote Manfred, and started on Don Juan, though his health was poor19.
Byron took Teresa, Countess Guicioli, as his mistress in 1819, and it was quite the scandal. Not just because the lady was married - Italian women were expected to have lovers - but because Byron often lived under the same roof with both Teresa and her rich old husband. He got involved with local politics in 1820, joining the Italian freedom fighters working for democracy20, though nothing really effective ever came of his plans. In 1822, Shelley drowned when his boat capsized, and the little group of English expatriates came apart. The following year, Byron became involved in the Greek fight for independence from Turkey. (Ironically, Ali Pasha, whom Byron had so admired, had been one of the Turkish oppressors of Greece.) Byron sailed for Greece at great risk and expense, even though he was convinced he was sailing towards his own death21. He joined forces with a Greek prince named Mavrocordato and financed a navy for the freedom fighters. Byron found himself reluctantly in command of everything, as the Greeks tended to fight amongst themselves too much.
In February of 1824, he had an epileptic seizure. Two months later, he was caught in a sudden storm while horseback riding, and he caught a chill from which he never recovered. He died on 19 April 1824, having suffered extreme delirium for many days. He was never able to read the letters of praise which had arrived from England a few days before, so he never knew that his native country had forgiven (or at least forgotten) his indiscretions.
Maurois, André. Byron. New York: Frederick Ungar Publishing Co., 1964.