Kotetsu gave the imperial side a uniquely armoured combatant. She displaced about 1,410 tons and carried a heavy rifled muzzle-loader with two additional large guns. Her waterline belt and protected gun positions offered defenses unavailable to the wooden and converted ships around her. Twin-shaft steam machinery provided a stated speed of roughly ten and a half knots and a range near 3,000 nautical miles. The design was awkward and inspired little confidence, but no local opponent combined comparable armour and firepower. That capability gap explains why destroying or capturing her became central to Ezo planning.
Notable Point · 1:34:22-1:37:05
Why Kotetsu overmatched Japan's wooden fleets
Kotetsu combined armor, heavy muzzle-loading guns, steam power, and a ram in the only ironclad then operating in Japanese waters.