Genetic manipulation was used to make the Space Marines stronger, faster, and tougher. At the same time, extensive surgery was performed to implant special organs to make them absolute masters of the battlefield.
The Space Marines have become the ultimate human soldier, though it could be argued that they are no longer still human. A Space Marine is well over seven
feet tall and easily able to crush a man's skull with his bare hands. Space Marines can fight for days at a time, heal wounds in minutes, and survive the most treacherous conditions. With his constant training, boltgun and power armour, the Space Marine is the most feared warrior throughout the galaxy.