Plutarch describes this formation as used by Mark Antony during his invasion of Parthia in 36 BC: If necessary, the legionaries on the sides and rear of the formation could stand sideways or backwards with shields held as the front rows, so as to protect the formation's sides and rear this reduced the speed and mobility of the formation, but offered consistent defensive strength against opposing infantry and excellent protection against arrows and other missile attacks. The men in the back ranks would place their shields over their heads to protect the formation from above, balancing the shields on their helmets, overlapping them. The shields would be held in such a way that they presented a shield wall to all sides.

The first row of men, possibly excluding the men on the flanks, would hold their shields from about the height of their shins to their eyes, so as to cover the formation's front.

In the testudo formation, the men would align their shields to form a packed formation covered with shields on the front and top.

Rome total war testudo