The yellowing news clipping below shows Durban harbor clogged with shipping during the Suez Canal crisis of 1956. I remember this well: we used to count the ships sitting off the coast.
Egyptian president Nasser closed the Suez Canal for four months 1956-57, as the result of a complicated series of events involving Britain and France (in a secret military pact), with Israel, as aggressors, the U.S., the Soviet Union, and the United Nations lined up against them.
Ships that could not use the canal were forced to sail from Europe and the UK by way of the southern tip of Africa. Durban, with it's natural harbor, was the last port of call for vessels sailing to India and further east. The increased number of ships could not be berthed all at the same time, so they had to wait outside the harbor until there was space.
The Suez Canal was of great strategic importance during the world wars. Troop ships from Australia and New Zealand sailed through the canal. The waterway was also the main conduit for oil tankers sailing from the Middle East to the Mediterranean and beyond.
I also remember how amazed I was when my American classmates were clearly ignorant of the location of the Suez Canal!