I think its English
in South Africa their are 11 official languages which are Sepedi, Sesotho, Setswana, siSwati, Tshivenda, Xitsonga, Afrikaans, English, isiNdebele, isiXhosa and isiZulu.
He sought to revive and reconstruct wholly the old empire
South African language suffered several changes because of the invasions. Before the Europeans San and Khoekhoe people were the first inhabitants. Then Europeans arrived, first were the Dutch and then Britain, that's why South Africa has so many languages.
Also, through historians we know that the first explores were from Portugal, after that came the Dutch colonisation between 1652 and 1815. Then the British arrived between 1815 and 1910.
So, these events explained the language diversity.
When the dutch and the English began to settle the southern tip of Africa there were not many native people. As the Boer(Dutch) moved inland and dominate the native people Dutch language usage increased. After the Boer war of the late 1800s English language dominated and became the official language of South Africa and continued through apartheid and afterwards