Was the capture of the blockade-runner Pocahontas a SIGINT success?

On the morning of July 9, 1864, Acting-Master Frederick W. Strong, commanding the tug-boat USS Azalea reported the capture of the Confederate schooner Pocahontas the night before:

I respectfully report the capture at 11:30 p.m., July 8, of the schooner Pocahontas, of and from Charleston, S.C., bound to Nassau, New Providence, with a cargo of 53 bales of cotton and 299 boxes of tobacco.

She was boarded simultaneously by boats of this and the USS Sweet Brier, the officers of both boats claiming precedence in boarding.  I would prefer that a prize crew be detailed from the Sweet Brier, as I have no officers to send in her.

The following papers were found in the possession of her captain: Clearance from port of Charleston, S.C. to Nassau, New Providence. Manifest of cargo and register.

Strong goes on to mention the captain of the Pocahontas, Joseph G. Hester, had on board the uniform of a lieutenant of the Confederate Navy.  Hester “being desirous of leaving the Confederate States,” had put his personal finances into the purchase of the blockade-runner and cargo.  Hester and his wife attempted passage on the Pocahontas.  Captain Joseph F. Green, senior officer on the blockade off Charleston at the time, added in his report that Hester offered information about the situation in Charleston:

He states that there are at Charleston three ironclads ready, and the rebels are hastening the completion of another on the stocks, and putting on extra thickness of plating, several shots from Morris Island having penetrated her.  Common report at Charleston says when she is ready a raid will be made by the rams and torpedo boats on the vessels at this anchorage. That the steamer Fox was to start out last night, but broke down.  That there were but seventeen men in Fort Johnson when the attack was commenced by the army.  That the rebels are expecting an attack on Fort Sumter by us and are making preparations to meet it.

A lot of leads in that paragraph.  The damage reported to the ironclad then under construction lends weight to the justifications for bombarding Charleston.  And the mention of just 17 men at Fort Johnson, though a gross under-statement, confirmed the lost opportunity from the morning of July 3.  Lastly, keep in mind for the moment the Steamer Fox was in Charleston and making ready for a run.

But something not mentioned in the reports is how the two Federal tugs came upon the Pocahontas.  Normally successful captures of this type start with the captain recalling the weather, the first sighting of the vessel, direction and course taken by the runner, and any actions required to intercept the vessel.  In this case, there are none.  No shots fired. No maneuvers required to intercept.  Just that boarders from the two tugs captured the runner.  Perhaps there were no details to relate?  Maybe the two tugs were, by chance, positioned at the right place, with crews at the ready when the Pocahontas made the run out?

Or, let me offer another possibility – the Federals were watching for a signal to indicate when the Pocahontas was setting sail.  Recall the work of Sergeant John D. Colvin on Morris Island, breaking the Confederate signal codes.  One of the deciphered messages from July 2 read:

Captain G.:

Schooner Pocahontas will be allowed to go out to sea to-night. Same signals will be used as arranged for last night.

Read, Captain.

There are several reasons why the Pocahontas wouldn’t have made a run out on the night of July 2-3, if as the message indicates was planned.  Not the least of which was all the Federal activity between Morris Island and Fort Johnson.   But this message does show the Federals knew the Pocahontas was preparing for a trip out and that signals were arranged between stations in and outside Charleston harbor.  Knowing that, were the Federals tipped off by the signals on the night of July 7?

One other interesting note in regard to Confederate signal lights.  On July 10, the Federals decoded several messages mentioning night-time signal lights, in a conversation Confederate stations at Breach Inlet and Battery Bee on Sullivan’s Island, at around 1:50 a.m.:

What is the meaning of those lights on the beach?

The response:

They are ordered to light the channel for ——–.

And:

You will please use a fort light hereafter.

Elements to ponder here.  The Pocahontas used Maffitt’s Channel parallel to Sullivan’s Island, intending to clear the bar somewhere off Breach Inlet.  And, as mentioned in Green’s report, the Confederates were preparing another blockade-runner – the Fox – for passage at that time, making her a candidate for the lost name in the response above.

Just offering this up as a possibility:

  • Federal signal troops intercepted a message on July 2 alerting the Navy about a blockade-runner.
  • Crews on the blockaders notice a pattern of lights that night, even though the Pocahontas didn’t make the run.
  • Several nights later, seeing the same pattern of lights, Federal ships move in to quietly intercept.
  • To keep secret that they knew the Confederate “secrets,” no mention of the lights is made in Federal reports.
  • Later, sensing the Federals were on to the signals, the Confederates change their light patterns.

I give it a fifty-fifty at best. One of those possibilities that always ends up one document short of being proven.

Still, the capture of the Pocahontas is a vignette of the blockade.  Not all the incidents in the game between runners and blockaders involved fast cruisers slipping anchors on a stormy night to chase down sleek steamers laden with valuable cargo.  Some of those stories involved unglamorous tug-boats.

(Citations from ORN, Series I, Volume 15, pages 563-4; OR, Series I, Volume 35, Serial 66, pages 550 and 579.)