A large section of the Clydesdale colliery at the Coalbrook mine near Sasolburg, Orange Free State, caved in and trapped 435 (or 440) mineworkers 180m underground in the worst mine disaster in South African history.
There were no survivors. No machine capable of drilling holes large enough through which to rescue people was available anywhere in the country.
Following this incident, the Chamber of Mines decided to purchase a suitable drill that would make it possible to reach men trapped underground in coal mines. -Sahistory
http://www.sahistory.org.za