Fortifications never went anywhere.

Just in this century, the US used fortified camps in Iraq and Afghanistan, and so did the French in Sahel. And the Ukrainians fortified Dombas and effectively prevented the Russians to take it quickly. Then the Russians fortified the Zaporizhzhia frontline (the Surovikin line) which stopped the Ukrainian counter offensive in 2023.

And talking about Africa in particular, the border between Morocco and Algeria, and also Western Sahara, has been a fortified wall for the past 40 years now.