ossed at night, surprised the Persians who held the opposite
bank, and established themselves in a safe position before the dawn of
day. By this bold exploit the passage of the other troops, many of whom
could not swim, was rendered feasible, and Jovian proceeded to collect
timber, brushwood, and skins for the formation of large rafts on which
he might transport the rest of his army.

These movements were seen with no small disquietude by the Persian king.
The army which he had regarded as almost a certain prey seemed about
to escape him. He knew that his troops could not pass the Tigris by
swimming; he had, it is probable, brought with him no boats, and the
country about Dura could not supply many; to follow the Romans, if they
crossed the stream, he must construct a bridge, and the construction
of a bridge was, to such unskilful engineers as the Persians, a work of
time. Before it was finished the legions might be beyond his reach, and
so the campaign would end, and he would have gained no advantage from
it. Under these circumstances he determined to open negotiations with
the Romans, and to see if he could not extract from their fears some
important concessions. They were still in a position of great peril,
since they could not expect to embark and cross the stream without
suffering tremendous loss from the enemy before whom they would be
flying. And it was uncertain what perils they might not encounter beyond
the river in traversing the two hundred miles that still separated them
from Roman territory. The Saracenic allies of Persia were in force on
the further side of the stream; and a portion of Sapor's army might
be conveyed across in time to hang on the rear of the legions and add
largely to their difficulties. At any rate, it was worth while to
make overtures and see what answer would be returned. If the idea of
negotiating were entertained at all, something would be gained; for each
additional day of suffering and privation diminished the Roman strength,
and brought nearer the moment of absolute and complete exhaustion.
Moreover, a bridge might be at once commenced at some little distance,
and might be pushed forward, so that, if the negotiations failed, there
should be no great delay in following the Romans across the river.

Such were probably the considerations which led Sapor to send as envoys
to the Roman camp at Dura the Surena and another great noble, who
announced that they came to offer terms of peace.