Titus Livius (Livy), The History of Rome, Book 34
Evan T. Sage, Ph.D. Professor of Latin and Head of the Department of Classics in the University of Pittsburgh, Ed.

39. At first the Lacedaemonians held up the Roman attack in the narrow approaches, and the three lines were fighting in different places at the same time; then, as the fighting grew more severe, the battle was by no means equal. [2] For the Spartans were fighting with long-distance weapons, from which the Roman soldier protected himself with great ease, partly by the size of his shield, partly because some javelins missed their mark and others fell only lightly. [3] For on account of the limited space and the throngs of soldiers, they not only had no room from which to hurl them on the run, which gives them the greatest momentum, but they lacked even room to try to throw them from an unimpeded and solid footing. [4] Consequently, of the weapons hurled from directly opposite none pierced the [p. 521]bodies, and few even the shields; [5] some of the Romans were wounded by troops on their flanks who occupied the higher ground; presently, as they advanced, some unexpected wounds were suffered from spears and even tiles hurled from the housetops. [6] Then they held their shields above their heads and fitted them so closely together that no space was left for random shots or even for the insertion of a javelin from near at hand, and having formed their testudo they forced their way forward. [7] The first narrow streets they entered, crowded with their own troops and those of the enemy, delayed them for a while; after they came out into the wider avenues of the city, gradually driving back the enemy, the violence of their assault could not be resisted longer. [8] When the Lacedaemonians had turned to flee, and in headlong flight were seeking the higher ground, Nabis too, trembling as if the city had been taken, looked about him for a way to escape; Pythagoras not only displayed the courage and performed the functions of a commander in other respects, but was, [9] moreover, the sole reason why the city was not captured, for he ordered the buildings nearest the wall to be set on fire. [10] When these had flamed up in an instant, and the men who ordinarily would be accustomed to bring aid to put out the fire were helping it to burn more fiercely, the roofs were collapsing upon [11] the Romans, and not only pieces of tile but half-burned beams were falling upon the soldiers and flames were shooting far out, while the smoke too was creating greater terror than danger. [12] And so those of the Romans who were outside the city and were just at that moment making their most violent attack, [p. 523]retired from the wall, and likewise those who had¹ already entered, lest they be cut off from their own men by the fire which was rising in their rear, fell back, and Quinctius, when he saw what the situation was, ordered the signal sounded for a retirement. [13] And so, when they had almost captured the city they were recalled and returned to their camp.