It was November 1975 when king Hassan signaled to his people to start the massive Green March. Western Sahara then was governed by Spain, but Franco had other things to keep him busy at the time and the armed forces didn't intervene. Soon thereafter most of Western Sahara was annexed by Morocco. The rest would follow in 1979.

There was some resistance though and in 1980 Morocco started work at the infamous Moroccan Wall which was finished after seven years and 2700 km.

Allegedly most of the length is a berm of sand and that time must have been a golden opportunity for our men at work. Morocco brought its own signs. They are of the French kind like in all countries in contact with them (see f.e. Saint Martin and New Caledonia).