Authored By Staff Writer (Updated: 3/2/2011): The testudo (or tortoise) was a revolutionary battlefield formation utilized by the Roman Empire. The formation of Roman soldiers utilized their shields in an interlocking fashion, effectively creating a type of tortoise shell to cover their forward advance while protected rearward elements in the formation from artillery attack alike. The forward elements of the formation would bring up their shields to protect their vital areas while the rearward elements raised their shields up and over the soldier in front of them. This provided maximum protection from enemy fire and allowed the testudo formation - albeit slowly - to advanced against a target line. The convex rectangular shields of the Romans were used to good effect in this way.
If the testudo had any weaknesses they lay in mobility and level of training. Seeing it that the unit required all soldiers to move in unison for maximum protection, the formation was about as fast as walking speeds. The formation also relied upon the training of the unit as individuals and as a whole which - for the Roman Army at least - was hardly an issue most of the time. If anything the legs might have been susceptible to enemy artillery at close range but by then, the testudo might break open and the legionnaires could be free to charge their targets. In many ways as their Phalanx counterparts, the testudo was a formation entirely dependent on their cohesion and command yet no so much susceptible to attacks from above and the flanks from artillery fire.
In any regard, the testudo formation was quiet cutting edge for the time as no other organized army fielded elements with this much cohesion and level of training. This in effect made the Roman Army far superior when compared to her contemporaries and makes it easy today for one to see how the Empire could expand as much as it did. Ingenuity was the name of the game for the Romans and the testudo formation is a great example of how they revolutionized ancient warfare.