Which fortification failure encouraged the increased use of concentric castles in medieval Europe?

💡 Explanation

Defenders could tunnel under walls, causing collapse; the concentric design mitigates this via subterranean counter-mines. Increased underground fighting occurred because undermining bypasses initial defenses; therefore, concentric castles became favored, rather than simply building higher walls.

• Which outcome resulted when the Roman-era Antikythera mechanism corroded in seawater?
• Which limitation influenced widespread sextant adoption despite their increased navigational precision?
• Which outcome arises when maize stalks decay within a raised Aztec chinampa?
• Which consequence resulted when the Roman road network experienced persistent overloading?
• Which critical impediment slowed large-scale Roman road construction?
• Which adjustment outcome occurred due to precession observations using medieval astrolabes?