Writing less than a year after the Civil War ended, Mark Twain had occasion to see a demonstration of the considerable skills of officers of the Signal Corps—the unsung masters of battlefield communication

It’s more or less a lost art in this age of satellite communications, but the two in this account would make for some unbeatable charades partners. Here's Twain's account of the demonstration in a West Coast newspaper:

from the Territorial Enterprise, February 1866

THE SIGNAL CORPS

Saw something the other night which surprised me more than my late investigations of spiritualism. It was some examples of the methods the United States Signal Corps [used] to telegraph information from point to point on the battle-fields of the rebellion. The Signal Corps "mediums" were Colonel Wicker, of the Russian Telegraph Expedition, and Mr. Jerome, Secretary of Mr. Conway of the same, both of whom were distinguished officers of Signal Corps throughout the war. Besides these two gentlemen there are only two other members of the corps on the coast.

In the late war a signal party was always stationed on the highest available point on the battle-field, and by waving flags they could telegraph any desired messages, word for word, to other signal stations ten miles off. At night, when torches were used, these messages have been read forty miles away, with a powerful glass. The flag, or torch, is waved right, left, up and down, and each movement represents a letter of the alphabet, I suppose, inasmuch as any villainous combination of letters and syllables you can get up can be readily telegraphed in this way with a good deal of expedition. These gentlemen I speak of sent messages the other night with walking-sticks, with their hands, their fingers, their eyes and even their moustaches! It is a little too deep for me.

One sat on one side of a large room, and the other at the opposite side. I wrote a long sentence and gave it to Jerome — he made a few rapid passes with his right arm like a crazy orchestra leader, and Colonel Wicker called off the sentence word for word. I confess that I suspected there was collusion there. So I whispered my next telegram to Jerome — the passes were made as before, and Colonel Wicker read them without a balk. I selected from a book a sentence which was full of uncommon and unpronounceable foreign words, pointed it out to Colonel Wicker, and he telegraphed it across to Jerome without a blunder. Then I gave Jerome another telegram; he placed two fingers on his knees and raised up one and then the other for a while, and the Colonel read the message. I furnished the latter with the following written telegram:

"General Jackson was wounded at first fire."

He went through with a series of elaborate winks with his eyes, and that other signal-sharp repeated the sentence correctly. I wrote:

"Thirteen additional cases of cholera reported this morning."

The accomplished Colonel telegraphed it to his confederate by simply stroking his moustache. There must be a horrible imposition about this thing somewhere, but I cannot get at it. They say that when they are in lecture rooms and parlors whence they are not close enough to speak to each other, they telegraph their comment on the company with their fingers, on their moustaches, or by gently refreshing themselves with a fan.

The signal Corps was one of the most important arms of the military service in the late war. It saved many a battle to the Union that must otherwise have been lost. Yet many of the officers of the army did not believe in its efficiency, regarded it as an ornamental innovation, and bore it strong ill-will. At the battle of Winchester, the officer in command after General Shields was wounded, had pressing need of reinforcements. The reserve were in full view six miles away. The Acting General asked a signal officer if he could order up a brigade. He said he could.

"Then do it," said the General; "but," said he, "to make everything sure, I will dispatch an orderly for the reinforcements." The signal officer set his flags waving, and telegraphed: "Send up a brigade on the double-quick." Before the orderly was a hundred yards off, the anxious General gazing through his field glass, saw a brigade wheel into the plain, peel their coats and knapsacks off and throw them down, and come sweeping across on the double-quick. "By G--. here they come! — send back the orderly," said the General — "but I didn't think it could be done.

[reprinted in The Washoe Giant in San Francisco, edited by Franklin Walker, (George Fields, 1938), pp. 131-33; reprinting the Golden Era, FEB. 18, 1866] Photo at top: Union signal station at Antietam, Library of Congress.