Nicholas felt that, because of Russian assistance in suppressing the Hungarian revolution of 1848, Austria would side with him, or at the very least remain neutral. Austria, however, felt threatened by the Russian troops in the Balkans. On 27 February 1854, the United Kingdom and France demanded the withdrawal of Russian forces from the principalities; Austria supported them and, though it did not declare war on Russia, it refused to guarantee its neutrality. Russia's rejection of the ultimatum caused the UK and France to enter the war.

In what year did the Hungarian revolution take place?