This memorial was erected towards the end of 1902, on the highest point in Johannesburg; Observatory Ridge.  It honours Hindus, Sikhs, Christians, Muslims and Zoroastrians members of the Indian Army that lost their lives in the Anglo Boer War.
Sadly the years and vandals have taken their toll on the monument and in the late 1980s some of the marble tablets were smashed. Originally written in Urdu, Hindi and English, only the English inscription still exists. The monument is not easily accessible and has been fenced off.
Geolocation
-26° 10' 58.8", 28° 4' 30"
References

https://allatsea.co.za/blog/the-indian-army-memorial-observatory-ridge-johannesburg/