Mickiewicz's childhood environment exerted a major influence on his literary work. His early years were shaped by immersion in Belarusian folklore and by vivid memories, which he later reworked in his poems, of the ruins of Navahrudak Castle and of the triumphant entry and disastrous retreat of Polish and Napoleonic troops during Napoleon's 1812 invasion of Russia, when Mickiewicz was just a teenager. The year 1812 also marked his father's death. Later, the poet's personality and subsequent works were greatly influenced by his four years of living and studying in Vilnius.His first poems, such as the 1818 ""Zima miejska"" ("City Winter") and the 1819 ""Kartofla"" ("Potato"), were classical in style, influenced by Voltaire. His "Ballads and Romances" and poetry anthologies published in 1822 (including the opening poem ""Romantyczność"", "Romanticism") and 1823 mark the start of romanticism in Poland. Mickiewicz's influence popularized the use of folklore, folk literary forms, and historism in Polish romantic literature. His exile to Moscow exposed him to a cosmopolitan environment, more international than provincial Vilnius and Kaunas in Lithuania. This period saw a further evolution in his writing style, with "Sonety" (Sonnets, 1826) and "Konrad Wallenrod" (1828), both published in Russia. The "Sonety", mainly comprising his "Crimean Sonnets", highlight the poet's ability and desire to write, and his longing for his homeland.