See Vassily Aksyonov's novel *The Island of Crimea* for the Crimea as a kind of Russian "Taiwan."
Ilya Somin (in *Stillborn Crusade: The Tragic Failure of Western Intervention in the Russian Civil War 1918-1920*) has suggested that there was a way to make an Aksyonov-like scenario a reality, even though the Crimea is a peninsula rather than an island. He points out that the Crimean peninsula is connected to the mainland only by two narrow strips of land that could easily be dominated by naval gunfire. "In fact, British naval units in the Black Sea had covered the inital White evacuation to the Crimea and prevented Red forces from intervening. They continued to give fire support to Wrangel's forces in the first few months of his command." (p. 187) Lloyd George, however, was determined to come to an agreement with the Bolsheviks and decided to end all support for Wrangel, despite Churchill's urgings. In June 1920 the British naval commander in the Black Sea was warned that "British Naval forces are to afford no, repeat no, support to Wrangel in offence or defence."
Somin thinks that it was well within the power of the British fleet to save the Crimean peninsula for the Whites, even after Britain had written off the rest of Russia. Of course that Britain would actually choose to do so seems pretty implausible, given the half-hearted nature of Allied intervention in the Russian Civil War (Somin is one of the few authors to regret the half-heartedness rather than the intervention). OTOH, it must have seemed pretty implausible in 1949 that the US, having refused to commit troops to prevent the Communists from taking over the Chinese mainland, would within a year be protecting Taiwan and would a few years later be on the verge of war with the PRC over a couple of tiny islands less than ten miles from the Chinese coast named Quemoy and Matsu...
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This is an old soc.history.what-if post of mine; for some posts casting doubt on whether the idea was practical, see
https://groups.google.com/d/msg/soc.history.what-if/1Cmxn8D-Yug/vHPAzVS8-o4J and
https://groups.google.com/d/msg/soc.history.what-if/1Cmxn8D-Yug/MoL3T7c0Lm4J Oh, well...