The Polish community in the United Kingdom since the mid-20th century largely stems from the Polish presence in the British Isles during the Second World War, when Poles made a substantial contribution to the Allied war effort. Most of the Poles who came to the United Kingdom at that time comprised military units reconstituted outside Poland after the German and Soviet invasions of Poland. ​ In the 20th century, a resurrected sovereign Poland enjoyed less than 21 years of relative peace before she was divided in 1939, in a fourth partition, between Germany and the Soviet Union. For the duration of the war Poland moved her government abroad, first to France and, after France’s fall, to London. Polish Air Force pilots played a conspicuous role in the Battle of Britain, and the Polish Navy conducted operations under the command of Britain’s Admiralty. The Yalta Conference (February 1945) place Poland within the Soviet sphere of influence. The great majority of Polish military veterans stranded in western Europe. These Poles and their familie, many of whom had experienced deportation to the Soviet Union, subsequently formed the nucleus of the post-war Polish community in Britain. A much smaller wave of Polish migration to Britain occurred with the imposition of martial law in Poland (1981–83), when individuals, mainly students and intellectuals who had been visiting the UK, chose not to return to Poland. The European Union’s 2004 enlargement, and the United Kingdom’s decision not to restrict immigration from the new accession states, encouraged educated and skilled Poles to migrate to the UK. As of 2016, the number of Polish-born UK residents was estimated at 911,000, making them the UK’s largest foreign-born community. Additionally, the UK’s Polish-descended population includes descendants of the over 200,000 Poles who had settled there after the Second World War. The Polish language is the second-most spoken language in England, and the third-most spoken in the UK after English and Welsh. About 1% of the UK population speaks Polish.