On 17 June 1940 the Red Army invaded Latvia and only three days later a new government of Soviet supporters was announced. They voted on 21 July for Latvia to become a part of the USSR and on 5 August this became official. The Soviet occupation saw around 35,000 Latvians deported to Russia within a year. In December 1940 the Latvian Society of Physicists and Mathematicians was closed down by the authorities who were particularly harsh on intellectuals (these formed the major part of those deported) and they also wished to stamp out any national feelings among Latvians.
The German army invaded the USSR in July 1941. For a period Latvia was a province of a larger Ostland (including Estonia, Lithuania, and Belorussia) and the Latvian Society of Physicists and Mathematicians tried to reopen its Society. It operated from January 1943 to May 1944 when again it was closed down through the renewed Soviet domination of Latvia.
On 4 May 1990 Latvian again declared its independence. There was a transitional period, marked by violence in Riga in January 1991, but by August 1991 Latvia had gained full independence. The Latvian Society of Physicists and Mathematicians was again restarted, but this time it became the Latvian Physical Society, and the Latvian Mathematical Society was founded as a new body in January 1993.
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