In 1879 South Africa, the administrators of the British Cape Colony have designs to eliminate the Zulus as a hindrance to their colonial economy. To that end, the British present King Cetshwayo with an impossible ultimatum to provoke a war they are sure they can win easily with their rifles and artillery against native spears. However, that war proves more difficult than the arrogant British commander, Lord Chelmsford, expects as his overburdened army fruitlessly searches for the elusive enemy. However, in the shadow of a hill called Isandlwana, the overconfident British army learns to its sorrow just how badly they have underestimated the tactical skill and might of the Zulu nation.

Cleopatra, the famed Egyptian Queen born in 69 B.C., is shown to have been brought by Roman ruler Julius Caesar at age 18. Caesar becomes sexually obsessed by the 18 year old queen, beds her, and eventually has a son by her. However, his Roman followers and his wife are not pleased by the union. In fact, as Caesar has only a daughter by his wife, he had picked Octavian as his successor. The out-of-wedlock son of Cleopatra is seen to be a threat to his future leadership. Thus Brutus and other Roman legislators plot the assassination of Caesar. Caesar's loyal general, Marc Antony, and Octavian then divide up the Roman empire. Antony takes Egypt and soon takes up the affair with Cleopatra. However, Octavian soon launches an attack on Antony and ultimately defeats and mortally wounds him. Rather than permitting herself to be humiliated by Octavian, Cleopatra sends her son away to India and she commits suicide by permitting the deadly asp to bite her.

Continuing the storyline of The Gathering Storm, Churchill at War is a look at the former British prime minister's life and career at the end of WWII.