Their religion was about war, their unorthodox weapon of choice was a battle-ax, and their brutal tactics terrorized Europe. The Viking warriors were strong, tough, and ruthless, destroying everything in their paths. With their homemade clothing and weapons, they would rely on their quick and ferocious strategies to ensure success, giving them a fearsome reputation throughout Europe.

A look at legendary crusaders the Knights Templar. Here, the focus is on knight Geoffroi de Champagne, who participated in and chronicled the Fourth Crusade. The Medieval period of history was extremely violent. Lands were regularly invaded, leading to long wars, frequent battles, and siege situations. This was the period of the Norman conquest and the Battle of Hastings. Warfare strategy, tactics, and weapons technology were transforming to adapt to these new battle situations.

Well-known for their ferocity, the Celtic population once dominated most of Europe. Though conflict and war were daily occurrences, throughout the Celtic culture there was a great admiration of heroic deeds, a religion based on sacrifice, and a fight for the greater good. Once united and fighting for the same cause, the Celts became a dangerous enemy - ferocious in battle and not to be tampered with.

Of all the greatest ancient warriors, the Romans were perhaps the most pragmatic. The Roman legions were the backbone of the Roman army, composed of up to 5,400 soldiers. They were masters of the sword and spear and could afford to make the best weapons and armour. Regarded as the prime ancient model for military efficiency and strategy, they were instrumental to Rome's unrivaled size and power.

No warrior has been more romanticised than the Scots Rebel Clansman. In Scotland, just over 700 years ago, Fraser Donnachaidh lived it for real.