Events in Latvia shortly before the first occupation

Events in Latvia shortly before the first occupation
In early summer 1940, when Germany had achieved most of its war objectives in the west, the Soviet Union proceeded with the occupation of the three Baltic countries and East Romania. On 14 June, the Soviet Union started an air and sea blockade of the Baltic. Soviet submarines blockaded not only the shores of the three Baltic countries, but also of Sweden and Finland. On 14 June the USSR presented the government of Lithuania with an ultimatum, and occupied Lithuania on 15 June. Simultaneously, Soviet army units attacked three Latvian border posts. On 16 June the USSR presented the governments of Latvia and Estonia with an ultimatum, demanding the resignation of their governments and the acceptance of additional Soviet military forces in their territories. The president of Latvia, Kārlis Ulmanis, and the government conceded to the ultimatum. The government of Estonia did the same.
On 15 and 16 June 1940, while a Latvian song festival was taking place in Daugavpils, Latvian border posts were attacked, Lithuania was being occupied, and the USSR ultimatum was presented to Latvia and Estonia. As a result of the attacks on the border posts, there was a strong sense of unease. President Ulmanis cancelled his trip to Daugavpils and addressed the festival's participants via radio. Then the assembled choirs and audience together sang the national anthem of Latvia three times. This was the last major event in independent Latvia.