&gt; Anyway, that raises a philosophical question: if your troops and their supplies need to be delivered across the water, and if your enemy is controlling that water, how much are you controlling the land behind?<p>Depends on how much that is true.  Replacements are definitely a problem, but medieval armies had significant ability to supply locally.  On top of this, the Toyotomi army was never blockaded on the peninsula; Yi&#x27;s actions significantly disrupted the sea lines of communication but never truly cut or controlled them.<p>Without the Ming army to fight Toyotomi would not have been under significant strain.  Even with a Ming army on the field and Yi disrupting his SLOC Toyotomi was still able to extract a truce while he held the southern half of the peninsula.<p>Regardless, what the Joseon navy was able to accomplish it did because Yi was a badass admiral, not because of turtle ships or other special weapons.  That was the original point.