On this day we are told by Pvt. Peter Perrine, Company C, that the left wing of the regiment remained in camp, several miles northwest of Alexandria, Louisiana. This portion of the 16th Ohio was part of the Union force defending Alexandria from harassment by Rebels while other soldiers, including the right wing of the 16th Ohio, continued work on building a dam across the Red River. This dam was being constructed to cause the water level in the river to rise, several miles upstream, so that 11 Federal gunboats, under the command of Adm. David Porter and stranded above the falls, could pass over the rapids and to the safety of deeper waters.

Early this morning, about 5:30 am, Union officers noticed that two barges used to plug the main dam, now nearly completed, had broken loose. Water was rushing through the gap in a great torrent. This break in the dam occurred before anyone was ready but quick action was taken to try and take advantage of the situation. The break in the dam was actually an event that was being planned in a few days.Several of the Federal boats had already passed over the upper falls the day before and were waiting in the pool just above the main dam. Adm. Porter, seeing the break, immediately ordered the U.S.S. Lexington to pass through the break. The action is described in military accounts of the event as follows:

Unfortunately, at five o'clock on the morning of the ninth, the pressure of the water became so great that it swept away two of the large coal barges that were sunk at the end of the dam near the centre of the river. When the accident was observed, the Admiral rode to the point where the upper vessels were anchored and ordered the Lexington to pass the upper falls, if possible, and immediately attempt to go through the opening in the dam, along which the water was rushing as fiercely as over the rapids at Niagara. The Lexington succeeded in getting over the falls and then steered directly for the opening in the dam, through which the water was dashing so furiously that it seemed as if certain destruction would be her fate. Ten thousand spectators breathlessly awaited the result. She entered the gap with a full head of steam; passed down the roaring, rushing torrent ; made several spasmodic rolls ; hung for a moment, with a harsh, grating sound, on the rocks below ; was then swept into deep water, and rounded to by the bank of the river. Such a cheer arose from that vast multitude of sailors and soldiers, when the noble vessel was seen in safety below the falls, as we had never heard before, and certainly have not heard since. Then all eyes were turned above the dam again, when another iron-clad was to be seen approaching. She did not fare as well as the Lexington, being considerably injured in the passage; but the other two passed through without any accident. It was perhaps a fortunate circumstance that a portion of the dam was carried away in the manner that it was, as the two barges that were forced out by the terrific pressure of the water swung round against some dangerous rocks, making a cushion for the vessels, and doubtless preventing, as afterwards appeared, the certain destruction of a portion of the fleet.

A total of four gunboats successfully made it through the lower rapids on this day. But the dam now needed repair before the rest of the fleet, still stranded above the upper falls, could proceed.

See more detailed and complete descriptions of Bailey's Dam in the Red River Campaign section.

This map shows the upper rapids, above which the Federal gunboats had been stranded by low water for several weeks and the lower rapids where the main dam was being built.When this main dam broke on the morning of May 9, several gunboats (as described above) quickly maneuvered and passed through the break, over the lower rapids and into the deeper water, below.