The V1 (known to the Germans as a FZG-76 as it was designed by the Fiesler company) was an unmanned, unguided, flying bomb. It was a simple concept, but a radical one.

The Germans designed a liquid fueled, pulse jet drone aircraft that could carry a 2,000 pound warhead to Southern England. They overcame the problem of unmanned navigation by simply pointing it in the correct direction, setting some simple gyrocompasses to keep it level and putting just enough fuel in it to get it to their target, typically a city in Southern England. 

They didn't much care what the rocket hit. It was a terror weapon, and it worked.

The V1 was powered by an Argus Schmidt pulse jet that made a characteristic putt-putt-putt sound as it went overhead. The motor carried them along at speeds up to 350 mph. They flew between 3,000 and 5,000 feet altitude. Their range was only 250 miles, so the launch sites had to be close to the coast to hit southern England.

The body was a simple steel tube with a fuel tank, a 2,000 pound warhead, and a simple guidance system.

The pulse jet motor was attached above the body at the back of the rocket. The short, rudimentary wings were made of wood.

It was a simple, medium range flying bomb, that was not very effective. 

The first V1 flew in 1942 at Peenemunde on the southern Baltic coast. 

A series of fixed launching sites were constructed in France, Holland, Denmark, and Germany to allow the Nazis to shower V1s on any part of southern England. However, Nazi planning did not take into account a strong bomber and fighter bomber offensive against the V1 launch sites. This forced the Nazis into creating mobile launch sites and launching some from Heinkel 111 bombers. 

The first offensive launch was on June 12, 1943. Once the Nazis got their stride they launched an average of 190 V1 rockets a day. 

The British quickly became expert at spotting and shooting them down, only about 25% of the V1s ever hit their targets. They established defensive zones, first were the fighters (Mosquitos, Spitfires, and Typhoons) over the English channel, then came a thick zone of heavy Anti Aircraft (AA, we, my friends and I called them ACK ACK guns. That was the kind of sound that they made) guns fitted with the first proximity fuses, then a zone of light Anti Aircraft guns and rocket projectors and finally there were the barrage balloons. These were very large helium filled balloons in rows and at different elevations. Fixed to the balloons and hanging down from them were very long lengths of heavy logging chain. 

Some of the fighter pilots would fly alongside the doodlebugs and a little below them, then when their wing was directly underneath the bombs wing the pilots would start to make a slow roll, this would cause an air cushion between the two wings and would cause the bomb to twist away.  This action would cause the gyro pilot to fail and the bomb would crash into the channel. 

This was told to me by my uncle Bob who was a spitfire pilot during the war. I never found out from him whether he was one of those who pulled off that stunt. I do know however, from my Dad, that uncle Bob did shoot down 6 enemy aircraft. 

Once the Allies captured the launching sites the target of choice switched to Antwerp, the main allied port. It received a pounding by 11,988 V1s and most of the 1,766 V-2 missiles launched. Fortunately, for the Allies they over ran the launch sites that could have deluged the Normandy beachhead with high explosive bombs, interfering greatly with the supply and logistics of an army in Europe.