With Germany home to 60% of the British Army's firepower, a training range in Fallingbostel is a good place to find out what makes a great tank crew.
By Chris Summers
BBC News Online in Fallingbostel, Germany
And in an age of computer games, it should be no surprise that a teenager is given the task of aiming and firing a Challenger 2 tank.
The Challenger 2 saw significant action in Iraq last year
Trooper Gareth Harley, from Wolverhampton, is only 18 but his commanding officer said he was so good he was made a gunner without undergoing driver training.
Second Lieutenant Rob Moseley, 24, from Cheltenham, Gloucestershire, was commissioned in August last year and is the youngest officer in the 7th Armoured Brigade's Badger squadron.
The brigade, better known as the Desert Rats, took part in the invasion of Iraq last year.
Three days after Lt Moseley was commissioned he was sent to Iraq for what he described as a "baptism of fire".
The tank's commander is always an officer but the other three men in the crew are ordinary soldiers.
Commander: 2nd Lt Rob Moseley, 24, from Cheltenham, Glos - in overall command, in charge of navigation
Operator: Cpl Ben Edwards, 31, from Edgware, north London - responsible for radio and other communications. Also cooks for the crew.
Gunner: Trooper Gareth Harley, 18, from Wolverhampton, West Midlands - responsible for aiming and firing the main cannon and choosing ammunition
Driver: Rick Tittle, 21, from St Vincent in the Caribbean - responsible for engine and track maintenance
Lt Moseley said: "There is a hierarchy - there has to be - but we work as a team.
"You start off as a driver because everybody has to learn how to drive the tank. You then move up to become the gunner and finally the operator, who is usually a corporal or lance corporal and quite an experienced soldier.
"I am the commander and the ultimate responsibility rests with me. But if I were to be killed or incapacitated the operator would take over, and so on. Everyone should be able to everybody else's jobs."
Lt Moseley, a graduate in psychology, said: "You have to have a close bond between the four people in a tank. I have only been working with these guys for six weeks but eventually I won't even need to tell the driver what to do.
"We'll be a homogenous unit and will be spending long periods cooped up inside the tank together."
There are 14 tanks in a squadron. Two are under the direct control of the squadron's commander. The other 12 are divided into four troops of three.
A troop leader is therefore not only in charge of his own tank but also two others, and he must remain in contact with the rest of the squadron.
'Superb bit of kit'
A Challenger 2 weighs around 68 tons and its top speed, when fully loaded, is 45 miles per hour. Each cost about £5.6m. They are built at Alvis Vickers' factories in Newcastle and Leeds.
Trooper Harley said: "It's a superb bit of kit. We can hit a target from several miles away, which is pretty good considering how small the targets are."
British firepower in Germany
176 Challenger 2 tanks (some currently based in Shaibah, southern Iraq)
273 Warrior armoured fighting vehicles
59 AS90 self-propelled artillery guns
11 Lynx and Gazelle helicopters (based at Gutersloh)
The British Army uses a mixture of kinetic ammunition, which does not rely on a high explosive charge, and Hesh (high explosive squash head) ammunition.
Lt Moseley says Hesh would be totally ineffective against modern tanks.
He explains how kinetic ammo works: "It's an armour-piercing, fin-stabilised projectile travelling at 2km per second. It will hit a tank and create a vacuum, sucking everything outside. If you were hit by one you wouldn't know anything about it - you'd be dead."
The Challenger is fitted with the most advanced armour in the world - known as Dorchester - which is designed to protect it from a direct hit from the enemy.
During the 1930s the Fallingbostel training range was used by Hitler to train two Wehrmacht divisions for the invasion of Poland.
Nowadays the training is somewhat different. Lt Moseley's crew spend days training to get into range to strike an imaginary enemy and manoeuvring to avoid being hit by the enemy.
Live firing phases
It is all done by computers and lasers.
Lt Moseley explains: "The tank emits a laser and it takes a reading, taking into account temperature, crosswinds, pressure etcetera and works out an 'elevation quotient'.
"You should then know that it will hit the target at that range. It's very accurate, even over four or five kilometres."
The computer will also estimate whether their own tank has been hit.
Occasionally the crew take part in live firing phases in which artillery fire comes within 400 metres and real shrapnel hits the tank.
As Lt Moseley says: "It is designed to test how you react to incoming fire."