The Harlequin Opal, Volume 3 by Fergus Hume

The squadrons move across the plain, Beneath a rain Of deadly missiles falling, falling. Oh, could we gain Those heights beyond, where guns are calling, Of deeds appalling, One to the other not in vain, Then might we conquer in the fray, And victors be e'er close of day.

The stream lying between the two armies was called the Rio Tardo, from its slow-flowing current, and emerging from the interior mountains, pursued its way in many windings to the sea. Centeotl was built on the left bank, so that the loyalists were unable to occupy the town without crossing the river, and to do so they would have had to force a passage at the point of the sword. The battle took place about three miles from the city, on a large plain streaked here and there with low ranges of sandy hills, and intersected by the broad stream of the Rio Tardo.