Which conflict involved the British Empire and resulted in the annexation of the South African republics?

The Second Boer War, which occurred from 1899 to 1902, was a pivotal conflict between the British Empire and the two Boer republics in South Africa—namely the South African Republic (Transvaal) and the Orange Free State. The war stemmed from escalating tensions over British imperial policies and the rights of the predominantly Dutch-speaking Boer settlers. Following a prolonged and brutal conflict characterized by guerrilla warfare and significant casualties on both sides, the British emerged victorious.

As a result of this war, the British annexed both the South African Republic and the Orange Free State, solidifying British control over a significant portion of southern Africa. This annexation integrated these territories into the British Empire, impacting the region's political landscape for decades to come.

The other conflicts listed do not relate to the annexation of the South African republics. The American Revolution primarily involved the thirteen colonies in North America seeking independence from British rule. The Civil War was a domestic conflict in the United States over issues like slavery and states' rights. World War I was a global conflict primarily involving Europe and did not relate to British territorial expansion in South Africa. Thus, the Second Boer War stands out distinctly as the conflict associated with the annexation of the South African