On Guard of Peace, for narrator, mezzo-soprano, chorus, boys' chorus and orchestra, op. 124

On Guard for Peace (Russian: На страже мира, romanized: Na strazhe mira), also translated as On Guard of Peace, Op. 124 is an oratorio by Sergei Prokofiev scored for narrators, mezzo-soprano, boy soprano, boys choir, mixed choir, and symphony orchestra. Each of its ten movements sets texts by Samuil Marshak, who had collaborated previously with the composer in the work Winter Bonfire, Op. 122.

Prokofiev composed On Guard for Peace under difficult personal circumstances. He had been among six composers censured by the Union of Soviet Composers in its 1948 Anti-Formalist Resolution on Music, which had immediate professional and financial consequences for him. The resulting stress exacerbated his chronic health problems from hypertension, which led to a stroke in 1949. Against his doctors' advice, Prokofiev wanted to compose a large oratorio on the theme of world peace, which he hoped would result in a paid commission from the Union of Soviet Composers or the Committee on Arts Affairs. With help from Alexander Fadeyev and Sergey Balasanian, Prokofiev was granted a commission for his oratorio from the children's programming division of the Radio Information Committee.