Concentration means rapid union, not one mass

The video rejects the familiar classroom opposition in which Mahan supposedly demands decisive concentration while Corbett rejects it. Corbett instead makes readiness for rapid action the guiding feature of preparation for war and says fleet distribution should still be dominated by concentration. His crucial distinction is that keeping forces together does not require holding every ship in one mass. Because the decisive point is harder to predict at sea, ships should be positioned to cover requirements and then unite quickly when that point emerges. Distribution can also conceal intentions, whereas a single visible mass may tell the enemy where the main effort will fall.