Tarzan the Untamed by Edgar Rice Burroughs

Tarzan was not yet fully revenged. There were many millions of Germans yet alive -- enough to keep Tarzan pleasantly occupied the balance of his life, and yet not enough, should he kill them all, to recompense him for the great loss he had suffered -- nor could the death of all those million Germans bring back his loved one.

While in the German camp in the Pare Mountains, which lie just east of the boundary line between German and British East Africa, Tarzan had overheard enough to suggest that the British were getting the worst of the fighting in Africa. At first he had given the matter but little thought, since, after the death of his wife, the one strong tie that had held him to civilization, he had renounced all mankind, considering himself no longer man, but ape.