Underway replenishment was the U.S. Navy’s secret weapon of World War II.
Fleet Admiral Chester Nimitz,
United States Navy
The essence of flexibility is in the mind of the commander; the substance of flexibility is in logistics.
My logisticians are a humorless lot…they know if my campaign fails, they are the first ones I will slay.
Throughout the struggle, it was in his logistic inability to maintain his armies in the field that the enemy’s fatal weakness lay. Courage his forces had in full measure, but courage was not enough. Reinforcements failed to arrive, weapons, ammunition and food alike ran short, and the dearth of fuel caused their powers of tactical mobility to dwindle to the vanishing point. In the last stages of the campaign they could do little more than wait for the Allied advance to sweep over them.
Dwight D. Eisenhower on Logistics
British Army Doctrine Publication, Volume 3, Logistics (June 1996) p. 1-2
Here they come!