Which outcome occurred in Roman sieges when attackers tunneled under city walls lacking bedrock foundations?

💡 Explanation

When tunnels were dug under walls without bedrock, soil compaction occurred because the walls' weight exceeded the soil's bearing capacity, leading to ground subsidence and ultimately wall collapse. Therefore, wall subsidence results, rather than groundwater flooding, poison gas build-up or spontaneous combustion, which require different geological conditions or mine tactics.

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