This plaque is at the bottom of a flagpole near the Clock Tower and pedestrian bridge in the Cape Town Waterfront.
The text at centre bottom reads:

Johan Daniel Stephan, a Dutch East India soldier from Germany, traded in grain and fish. Based in St. Helena Bay, his descendants dominated the west coast trade.

The Norwegians Arnt and Matthias Thesen built up a shipping line on timber from the Knysna forests after 1869.

In 1966, Thesen's Shipping Company merged with African Coasters and Smith Coasters of Natal to form Unicorn Lines, thereby expanding their activities further round the South African coast. This flagmast also shows the extent of their world-wide trade.