In 1967, Israel launched a preemptive strike against hostile neighbors Egypt, Syria and Jordan, and in the process took control of some hotly contested land. About 30 seconds after that, Egypt, Syria and Jordan wanted some payback.
"Oooh, you guys are dicks."
Now, Israel wasn't stupid; they knew their Arab neighbors were plotting revenge. However, based on intelligence estimates, they calculated that Israel didn't need to worry about an attack until at least 1975. Meanwhile, around 1973, smart individuals in Israeli intelligence started noticing moves that troubled them, almost like Egypt and Syria were getting ready to, you know, start a war. But with 1975 still two years away, these people were fairly well ignored.
"Those are probably peace tanks."
Israel didn't realize that their enemies were actually in far better shape than they thought they were. Pretty much everyone was feeding Israel misinformation, and the other side was steadily being armed by the Soviets.
Still, the Israelis were so confident that no attack was coming that when the freaking King of Jordan flew in to say, "Yeah, they're totally gonna attack you, and I know because they asked me to join them," no one believed him.
When Yom Kippur rolled around, Israel initiated a partial call-up of their reserves, but otherwise the holiday was set to go on as normal. Meanwhile, the "surprise" attack started: Egyptians breached Israel's so-called Bar Lev Line without much difficulty and began pouring into the Sinai, while the Syrians retook most of the Golan Heights in their attacks.
But It Turned Out ...
Israel's lack of preparation allowed a massive Egyptian army into the Sinai unimpeded. This would wind up spelling doom ... for the Egyptians.
"Oh shit, we forgot to bring enough army!"
That's because Israeli forces managed to reseal the Bar Lev Line, which had the effect of trapping an entire Egyptian army in the Sinai. When it came time to negotiate a settlement, Israel found itself with a nice bargaining chip in the form of said trapped Egyptian army. They didn't really want the Sinai so much as they wanted Egypt to leave them the hell alone. So they proposed a deal: They'd let Egypt have back both the Sinai and their army if they just agreed to recognize Israel's right to exist. Egypt took the deal.
Israel also managed to take the Golan Heights and offered it back to Syria for the same deal, but the Syrians weren't ready to accept Israel. Perhaps if Israel had a couple hundred thousand Syrian troops trapped there, things would have been different. It just demonstrates how fortunate they were that so many Egyptian soldiers managed to put themselves in a position to be trapped, and it probably would not have happened if Israel had actually been ready.
"Surprise wars are nice. There's a lot less stress, y'know?"
On "a date which will live in infamy," Japan attacked Pearl Harbor, Hawaii, on December 7, 1941. It pretty much sucked.
On November 28, 1941, the U.S. Chief of Naval Operations sent an encoded important warning message via commercial telegraph that warned of an imminent attack from Japan and advised the military to start flying reconnaissance missions to watch out for, say, Japanese fighters that were sent to attack Hawaii.
Why send such an important message by telegraph? Well, atmospheric conditions on that day made radio transmissions between Washington, D.C., and Hawaii impossible, and email hadn't been invented yet.
"We'd settle for AOL right about now."
Despite what the message said, army and navy planes at Pearl Harbor were not flying reconnaissance, and this didn't escape Japanese attention. This is because that message was received on the 6th of December, but wasn't translated until the 8th -- one day after the attack. Believe it or not, that was considered a short delay. Another message sent on November 24 giving a detailed report of goings on at Pearl was not translated until December 16.
As a result, the navy didn't sail out to meet the Japanese attack, everyone was caught by surprise, history happened.
America unleashed its horde of giants shortly thereafter.
But It Turned Out ...
If the U.S. military had been translating these in real time, there's a good chance the fleet would've been sortied (deployed to attack), especially when they read this urgent request from Tokyo on the 6th referring to an earlier message from the 2nd. But they didn't, and it wasn't. Which saved a whole lot of lives.
Why? Well, those ships would have been taking on Japanese aircraft. And, as many ships would find out during the war, it would have been suicide. Ships at the time just weren't equipped to defend themselves from air attack.
Most of the American fleet had ditched its AA for high-quality surround sound systems.
For instance, the British found this out for themselves three days after the attack when Japanese planes caught HMS Prince of Wales and HMS Repulse in open water. For the price of just three airplanes and 18 men, the Japanese sunk both ships, with a total loss of over 800 hundred men for the Allies.
Throughout the war there would be several more battleships sunk by airplanes, including both of the biggest battleships ever built (the Bismarck and the Yamato). Many sailors could have told you how it goes when ships take on aircraft carriers and the planes they carry.
We'll give you a hint: not well.
This is why Admiral Chester Nimitz said, "It was God's mercy that our fleet was in Pearl Harbor on December 7, 1941." Yes, the fleet was bombed in the attack. Eight ships sank. But there is a huge difference between ships getting sunk in the harbor (where crews were easily rescued and six of the ships saved) versus out in the open ocean (where those same ships would have wound up on the ocean floor, along with the 20,000 sailors on board).
In reality, the Japanese attack was pretty much a failure. The U.S. ended up losing only two battleships: Arizona and Oklahoma. Meanwhile, all the fuel and repair facilities at the base were left untouched, and the navy could get to work fixing them right away, which is exactly what they did. They were also able to send out the Pacific fleet submarines, fully fueled and stocked, within 24 hours of the attack. As for the remaining battleships, they got the Six Million Dollar Man treatment -- they were rebuilt with stuff like fire control radar and dual-purpose secondary armament (making them capable of shooting at airplanes and ships).
A few years later, we'd have a chance to show them the new improvements in person.
All because they stayed home on the day of the attack, thanks to the fact that nobody bothered to read their messages.
For more historic buffoonery, check out 5 Battlefield Screw Ups That Were Hilarious (Until People Died) and 5 Minor Screw-ups That Created The Modern World.