Percy Bysshe Shelley 1819
Mary Shelley 1840
After this break-up of his domestic life, Byron again left England, and, as it turned out, it was forever (until he returned after his death, despite his dying wishes). He passed through Belgium and continued up the Rhine river. In the summer of 1816 he settled at the Villa Diodati by Lake Geneva, Switzerland, with his personal physician, the young, brilliant, and handsome John William Polidori. There Byron befriended the poet Percy Bysshe Shelley, and Shelley's future wife Mary Godwin. He was also joined by Mary's stepsister, Claire Clairmont, with whom he had had an affair in London.
Kept indoors at the Villa Diodati by the "incessant rain" of "that wet, ungenial summer" over three days in June, the five turned to reading fantastical stories, including Fantasmagoriana, and then devising their own tales. Mary Shelley produced what would become Frankenstein, or The Modern Prometheus, and Polidori was inspired by a fragmentary story of Byron's, Fragment of a Novel, to produce The Vampyre, the progenitor of the romantic vampire genre.
Byron's story fragment was published as a postscript to Mazeppa; he also wrote the third canto of Childe Harold. Byron wintered in Venice, pausing his travels when he fell in love with Marianna Segati, in whose Venice house he was lodging, and who was soon replaced by 22-year-old Margarita Cogni; both women were married. Cogni could not read or write, and she left her husband to move into Byron's Venice house. Their fighting often caused Byron to spend the night in his gondola; when he asked her to leave the house, she threw herself into the Venetian canal.
In 1816, Byron visited San Lazzaro degli Armeni in Venice, where he acquainted himself with Armenian culture with the help of the abbots belonging to the Mechitarist Order. With the help of Father H. Avgerian, he learned the Armenian language, and attended many seminars about language and history. He co-authored English Grammar and Armenian (Kerakanutyun angğiakan yev hayeren) in 1817, and Armenian Grammar and English (Kerakanutyun hayeren yev angğiakan) in 1819, where he included quotations from classical and modern Armenian.
Byron later participated in the compilation of the English Armenian dictionary (Barraran angghieren yev hayeren, 1821) and wrote the preface in which he explained the relationship of the Armenians with and the oppression of the Turkish "pashas" and the Persian satraps, and their struggle of liberation. His two main translations are the Epistle of Paul to the Corinthians, two chapters of Movses Khorenatsi's History of Armenia and sections of Nerses of Lambron's Orations.
His fascination was so great that he even considered a replacement of the Cain story of the Bible with that of the legend of Armenian patriarch Haik. He may be credited with the birth of Armenology and its propagation. His profound lyricism and ideological courage has inspired many Armenian poets, the likes of Ghevond Alishan, Smbat Shahaziz, Hovhannes Tumanyan, Ruben Vorberian and others.
In 1817, he journeyed to Rome. On returning to Venice, he wrote the fourth canto of Childe Harold. About the same time, he sold Newstead and published Manfred, Cain and The Deformed Transformed. The first five cantos of Don Juan were written between 1818 and 1820, during which period he made the acquaintance of the young Countess Guiccioli, who found her first love in Byron, who in turn asked her to elope with him.
Led by the love for this local aristocratic and married young Teresa Guiccioli, Lord Byron lived in Ravenna between 1819 and 1821. Here he continued the Don Juan and wrote the Ravenna Diary, My Dictionary and Recollections. It was about this time that he received visits from Percy Bysshe Shelley, as well as from Thomas Moore, to whom he confided his autobiography or "life and adventures", which Moore, Hobhouse, and Byron's publisher, John Murray, burned in 1824, a month after Byron's death. Of Byron's lifestyle in Ravenna we know more from Shelley, who documented some of its more colourful aspects in a letter: "Lord Byron gets up at two. I get up, quite contrary to my usual custom … at 12. After breakfast we sit talking till six. From six to eight we gallop through the pine forest which divide Ravenna from the sea; we then come home and dine, and sit up gossiping till six in the morning. I don’t suppose this will kill me in a week or fortnight, but I shall not try it longer. Lord B.’s establishment consists, besides servants, of ten horses, eight enormous dogs, three monkeys, five cats, an eagle, a crow, and a falcon; and all these, except the horses, walk about the house, which every now and then resounds with their unarbitrated quarrels, as if they were the masters of it… . [P.S.] I find that my enumeration of the animals in this Circean Palace was defective … . I have just met on the grand staircase five peacocks, two guinea hens, and an Egyptian crane. I wonder who all these animals were before they were changed into these shapes." 
From 1821 to 1822, he finished Cantos 6–12 of Don Juan at Pisa, and in the same year he joined with Leigh Hunt and Percy Bysshe Shelley in starting a short-lived newspaper, The Liberal, in the first number of which appeared The Vision of Judgment. For the first time since his arrival in Italy, Byron found himself tempted to give dinner parties; his guests included the Shelleys, Edward Ellerker Williams, Thomas Medwin, John Taaffe and Edward John Trelawney; and "never", as Shelley said, "did he display himself to more advantage than on these occasions; being at once polite and cordial, full of social hilarity and the most perfect good humour; never diverging into ungraceful merriment, and yet keeping up the spirit of liveliness throughout the evening."
Shelley and Williams rented a house on the coast and had a schooner built. Byron decided to have his own yacht, and engaged Trelawny's friend, Captain Daniel Roberts, to design and construct the boat. Named the Bolivar, it was later sold to Charles John Gardiner, 1st Earl of Blessington, and Marguerite, Countess of Blessington, when Byron left for Greece in 1823.
Byron attended the funeral of Shelley, which was orchestrated by Trelawny after Williams and Shelley drowned in a boating accident on 8 July 1822. His last Italian home was Genoa, where he was still accompanied by the Countess Guiccioli, and the Blessingtons, providing the material for Lady Blessington's work: Conversations with Lord Byron, an important text in the reception of Byron in the period immediately after his death.
Byron was living in Genoa when, in 1823, while growing bored with his life there, he accepted overtures for his support from representatives of the movement for Greek independence from the Ottoman Empire. With the assistance of his banker and Captain Daniel Roberts, Byron chartered the Brig Hercules to take him to Greece. On 16 July, Byron left Genoa arriving at Kefalonia in the Ionian Islands on 4 August. His voyage is covered in detail in Sailing with Byron from Genoa to Cephalonia.
Byron historian Donald Prell, wrote of a coincidence in Byron's chartering the Hercules. The vessel was launched only a few miles south of Seaham Hall, where in 1815 Byron married Annabella Milbanke. Between 1815 and 1823 the vessel was in service between England and Canada. Suddenly in 1823, the ship's Captain decided to sail to Genoa and offer the Hercules for charter.
After taking Byron to Greece, the ship returned to England, never again to venture into the Mediterranean. "The Hercules was age 37 when on 21 September 1852, her life ended when she went aground near Hartlepool, only 25 miles south of Sunderland, where in 1815, her keel was laid; Byron's keel was laid nine months before his official birth date, 22 January 1788; therefore in ship-years, he was age 37, when he died in Missolonghi.
Byron spent £4,000 of his own money to refit the Greek fleet, then sailed for Missolonghi in western Greece, arriving on 29 December, to join Alexandros Mavrokordatos, a Greek politician with military power. During this time, Byron pursued his Greek page, Lukas Chalandritsanos, but the affections went unrequited. When the famous Danish sculptor Bertel Thorvaldsen heard about Byron's heroics in Greece, he voluntarily resculpted his earlier bust of Byron in Greek marble.
Mavrokordatos and Byron planned to attack the Turkish-held fortress of Lepanto, at the mouth of the Gulf of Corinth. Byron employed a fire-master to prepare artillery and took part of the rebel army under his own command, despite his lack of military experience. Before the expedition could sail, on 15 February 1824, he fell ill, and the usual remedy of bloodletting weakened him further. He made a partial recovery, but in early April he caught a violent cold which therapeutic bleeding, insisted on by his doctors, aggravated. It is suspected this treatment, carried out with unsterilised medical instrumentation, may have caused him to develop sepsis. He developed a violent fever, and died in Missolonghi on 19 April.
His physician at the time, Julius van Millingen, son of Dutch-English archaeologist James Millingen, was unable to prevent his death. It has been said that if Byron had lived and had gone on to defeat the Ottomans, he might have been declared King of Greece. However, contemporary scholars have found such an outcome unlikely.
Alfred, Lord Tennyson would later recall the shocked reaction in Britain when word was received of Byron's death. The Greeks mourned Lord Byron deeply, and he became a hero. The national poet of Greece, Dionysios Solomos, wrote a poem about the unexpected loss, named To the Death of Lord Byron. Βύρων ("Vyron"), the Greek form of "Byron", continues in popularity as a masculine name in Greece, and a town near Athens is called Vyronas in his honour.
Byron's body was embalmed, but the Greeks wanted some part of their hero to stay with them. According to some sources, his heart remained at Missolonghi. His other remains were sent to England (accompanied by his faithful manservant, "Tita") for burial in Westminster Abbey, but the Abbey refused for reason of "questionable morality". Huge crowds viewed his body as he lay in state for two days in London. He is buried at the Church of St. Mary Magdalene in Hucknall, Nottinghamshire. A marble slab given by the King of Greece is laid directly above Byron's grave. A duplicate of the slab was later placed in Westminster Abbey. His daughter, Ada Lovelace, was later buried beside him.
Byron's friends raised the sum of 1,000 pounds to commission a statue of the writer; Thorvaldsen offered to sculpt it for that amount. However, for ten years after the statue was completed in 1834, most British institutions turned it down, and it remained in storage. The statue was refused by the British Museum, St. Paul's Cathedral, Westminster Abbey and the National Gallery before Trinity College, Cambridge, finally placed the statue of Byron in its library.
In 1969, 145 years after Byron's death, a memorial to him was finally placed in Westminster Abbey. The memorial had been lobbied for since 1907: The New York Times wrote, "People are beginning to ask whether this ignoring of Byron is not a thing of which England should be ashamed ... a bust or a tablet might be put in the Poets' Corner and England be relieved of ingratitude toward one of her really great sons."
Robert Ripley had drawn a picture of Boatswain's grave with the caption "Lord Byron's dog has a magnificent tomb while Lord Byron himself has none". This came as a shock to the English, particularly schoolchildren, who, Ripley said, raised funds of their own accord to provide the poet with a suitable memorial. (Source: Ripley's Believe It or Not!, 3rd Series, 1950; p. xvi.)
Close to the centre of Athens, Greece, outside the National Garden, is a statue depicting Greece in the form of a woman crowning Byron. The statue is by the French sculptors Henri-Michel Chapu and Alexandre Falguière.
Upon his death, the barony passed to Byron's cousin George Anson Byron, a career naval officer.