Charles Spurgeon Commentary Nahum 3:12

"All thy fortresses shall be [like] fig-trees with the first-ripe figs: if they be shaken, they fall into the mouth of the eater." — Nahum 3:12 (ASV)

As figs do when they are ripe, these castles, towers, and fortresses, built to stand the siege, would no sooner be attacked than they would fall into the hand of the enemy.