Midway is not much. It is two small flat islands inside a coral ring, more than a thousand miles from Hawaii, with a runway, some fuel tanks and a great many seabirds.
It was valuable for exactly one reason, which is that it sits at the north-western end of the Hawaiian chain, and whoever holds it can watch the approaches to Pearl Harbor.
In June nineteen forty two the Japanese fleet came for it, with four aircraft carriers and a force so large that the Americans could not have matched it on any reasonable day.
The Americans were not there on a reasonable day. They were there because they had read the mail.
In a windowless basement at Pearl Harbor, a naval unit known as Station Hypo worked on Japanese naval codes. Its head was Joseph Rochefort, who wore a red smoking jacket and carpet slippers to work because the air conditioning was set for the machines rather than the people, and who had a habit of going for days without properly sleeping.
They were working on a code called JN-25, and they could not read it fully. They could read fragments, perhaps a tenth to a quarter of any given message, and from those fragments they reconstructed meaning.
By May nineteen forty two the fragments were pointing to a major operation against a place the Japanese messages referred to only as AF.
Rochefort was sure AF was Midway. Washington was not, and thought it more likely to be somewhere in the south, or possibly the American west coast. The disagreement mattered enormously, because the whole American fleet would be committed on the answer.
So Rochefort's team devised a test, and it is one of the neatest things anybody did in the whole war.
Midway was instructed, by secure undersea cable that no one could intercept, to send a radio message in plain uncoded English, saying that its fresh water distillation plant had broken down and that the island was short of water.
The message was deliberately not encrypted. Anybody could read it, which was the point.
Two days later, Station Hypo intercepted a Japanese signal reporting that AF was short of fresh water.
There is a detail worth adding. To be certain the trick had worked, the team also needed the Japanese to be using the water report themselves, and a second intercept a few days later, giving AF's position for a supply drop, confirmed the whole picture.
That was the whole proof. Admiral Nimitz now knew the target, and from further decrypts he had the approximate date and the order of battle.
Knowing was not enough. Nimitz had two carriers available against four, and a third, the Yorktown, had been badly damaged a month earlier in the Coral Sea.
She limped into Pearl Harbor trailing oil. The dockyard estimated the repairs at two weeks, possibly three.
Nimitz gave them three days.
Fourteen hundred men went aboard while she was still entering the dry dock, and worked without stopping for seventy-two hours. They did not repair the ship properly. They made her able to fight: patched the holes, shored up the frames with timber, restored power, and left the rest.
Welders worked in three shifts around the clock under floodlights, and the power for the dock was taken from the city, which meant parts of Honolulu had their electricity cut off for the duration without being told why.
She sailed on the thirtieth of May, with civilian workmen still aboard finishing jobs, and was in position north-east of Midway when the Japanese arrived, on the assumption that she was at the bottom of the Coral Sea.
On the morning of the fourth of June, the Japanese carriers launched a strike against Midway itself, and the aircraft came back reporting that a second strike would be needed.
So the Japanese admiral, Nagumo, ordered his reserve aircraft to be rearmed with bombs for another attack on the island. They were being rearmed when a scout plane reported American ships, including a carrier.
He changed the order back. Bombs off, torpedoes on. This is not a quick job. It meant hundreds of men working in the hangar decks with fuel lines out and ordnance stacked on the floor rather than returned to the magazines, because returning it took too long.
Meanwhile the American strike arrived, in pieces, badly coordinated, because the squadrons had launched from different ships and become separated.
The torpedo bombers found the fleet first. They were slow, they attacked low and level, and they went in without fighter escort because the escort had lost them.
The men flying them knew what was likely to happen. The aircraft type was obsolete, everybody said so, and the crews had discussed it among themselves before they left.
They were annihilated. Torpedo Squadron Eight from the Hornet lost all fifteen aircraft and scored no hits at all. One man survived, Ensign George Gay, who spent the rest of the day in the water watching the battle.
The torpedo squadrons achieved nothing they had been sent to achieve, and they decided the battle.
Attacking at wave height, they pulled the entire Japanese fighter screen down to sea level to slaughter them. Which meant that at about twenty past ten in the morning, the sky above the Japanese carriers was empty.
And into that empty sky came the dive bombers.
They had very nearly not arrived at all. One group, led by Wade McClusky from the Enterprise, had flown to where the Japanese should have been, found empty ocean, and was reaching the point of no return on fuel. McClusky spotted a lone Japanese destroyer far below, steaming hard on a north-easterly course, and reasoned that it was hurrying to rejoin the fleet. He followed its wake, and it led him to the carriers.
There is a second piece of good fortune stacked on the first. A group from the Yorktown, which had taken off nearly an hour later and by a completely different route, arrived over the fleet within a minute or two of McClusky's. Neither group knew the other was there. Two separate navigational gambles converged on the same patch of ocean at the same moment.
The dive bombers came down out of the sun onto flight decks crowded with fuelled and armed aircraft, and hangar decks stacked with the ordnance that had been swapped twice.
A single bomb into a wooden flight deck was survivable. A single bomb into a flight deck with fuel hoses run out, armed aircraft parked wingtip to wingtip and stacks of bombs sitting loose on the hangar floor was not, and that is what each of them found.
In something between five and six minutes, three of the four Japanese carriers were burning beyond saving. The fourth, Hiryu, launched a counter-strike that fatally damaged the Yorktown, and was found and destroyed that afternoon.
Japan lost four fleet carriers in a day, along with a large number of aircraft, and worse than either, several hundred trained aircrew and, crucially, its most experienced carrier mechanics and deck crews. Those people took years to replace and in practice never were.
Rochefort, whose basement made the whole thing possible, was rewarded by being removed from his post within months, largely because he had been right when Washington had been wrong and had not been graceful about it. He was recommended for a decoration and it was blocked. He finally received the Distinguished Service Medal in nineteen eighty five, ten years after his death.
It is worth being honest that luck ran through the whole day. McClusky's destroyer, the timing of the torpedo attacks, the state of the Japanese hangar decks at that particular minute. Preparation put the Americans in the right ocean. What happened in those five minutes was not entirely earned.
Here is something to think about tonight. Torpedo Squadron Eight flew into a battle they had no chance of surviving and hit nothing at all. Their attack is the reason the battle was won. Does it matter whether they knew that, and does it change anything about what they did?