Rostropovich played at The Proms on the night of 21 August 1968. He played with the Soviet State Symphony Orchestra – it was the orchestra's debut performance at the Proms. The programme featured Czech composer Antonín Dvořák's Cello Concerto in B minor and took place on the same day that the Warsaw Pact invaded Czechoslovakia to end Alexander Dubček's Prague Spring. After the performance, which had been preceded by heckling and demonstrations, the orchestra and soloist were cheered by the Proms audience. Rostropovich stood and held aloft the conductor's score of the Dvořák as a gesture of solidarity for the composer's homeland and the city of Prague.