The tone of Caesar and Cleopatra is highly satirical, seeping through in everything from Ra's speech in the prologue to the stage directions to Caesar's philosophizing. This satirical tone is often utilized to critique concepts of empire and imperialism, made most obvious in passages where either Caesar or Shaw himself—via stage directions—will undermine the idea of Roman might and superiority. Shaw uses a historical lens to critique early-20th-century imperialism, drawing direct connections between the British Empire of his time and the Roman Empire of antiquity.
Caesar's attitude toward Britannus, his servant from the British Isles, is especially telling. Note the following passage from Act 2, where Caesar accuses Britannus of barbarism:
BRITANNUS: [shocked] Caesar: this is not proper.
THEODOTUS: [outraged] How!
CAESAR: [recovering his self-possession] Pardon him, Theodotus: he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.
BRITANNUS: On the contrary, Caesar, it is these Egyptians who are barbarians; and you do wrong to encourage them. I say it is scandal.
Caesar speaks of Britian the way many of Shaw's contemporaries undoubtedly spoke about groups of indigenous people in colonized regions. This sets Shaw's tone as satirical, turning Britain's own colonial racism against it.