A "testudo" is a military formation used by the ancient Roman army, particularly the legionaries. In this formation, soldiers would align closely together, holding their shields overhead and on the sides to create a protective shell. This tactic was effective for advancing toward enemy fortifications while minimizing exposure to projectiles. The term "testudo" translates to "tortoise" in Latin, reflecting the shape of the formation. It allowed Roman soldiers to move as a unit, providing safety and cohesion during battles. The testudo was especially useful during sieges, where it helped troops approach walls without suffering heavy casualties.