Of American-English origin, the phrase like a headless chicken means in a panic-stricken and unthinking manner.

This phrase alludes to the phenomenon whereby a chicken can move about for a short time after decapitation, due to reflex activity of the nervous system.

For example, the following curious story was published in The Weekly Butte Democrat (Oroville, California) of Saturday 3^rd May 1862:

A Headless Chicken.—The San Francisco Herald relates the following:
One week ago, or thereabouts, a woman in the employ of Mr. Michael Kirk, of Tomales, Marin county, in the course of her preparations for dinner, cut off the heads of four chickens, one of them a vigorous young “Rooster.” Upon completing the sanguinary performance she was startled at the discovery that the number of bodies did not tally with the number of heads. There were four chicken heads on the block—sure enough, but only three chickens. There could be no mistake about it. The beheaded chanticleer had walked off leisurely after finding his head was off, and when next seen was standing upright at a distance of twenty yards from the scene of decapitation. A physician who was called in to examine the thing, found that there was not a particle of brain remaining, though the head was cut off very close; and how the chicken had sense enough to get up and walk away is a wonder. It was then resolved to try the experiment of prolonging the life of the bird, and up to the present writing it has been regularly fed with thin gruel by means of a syrringe [sic]. It has lived seven days, and gives every indication of continuing to enjoy life for a long time. The chicken is now in this city, and was visited by a number of persons on Saturday and yesterday. Mr. Benedict, who was kind enough to afford us a sight of the “rara avis” yesterday, has sent to Tomales for the head, and will shortly give a public exhibition of his novelty. As a “living tosic [= ?] without a head,” it is beyond question the most remarkable subject we have ever been called upon to indite a paragraph about. It has already excited some attempts at humorous comment.—A person who accompanied us to see the wonder yesterday, exclaimed: ‘A chicken-freak-i-see’ (!) But as the chicken in question so wonderfully escaped the fricassee, we are unable to see the point of the intended joke.—It may be proper to remark that the chicken has not crowed once since its head was taken off—though, we are informed, he has made several attempts to do so.

These are the earliest occurrences of the phrase like a headless chicken that I have found, in chronological order:

1-: From the Cleveland Plain Dealer (Cleveland, Ohio) of Wednesday 28^th September 1853:

The Free Soil party, which they had fondly hoped to “bring up in the nurture and admonition” of Whiggery, won’t come to the call—is divided and bewildered like a headless chicken, and all through their own exertions.

2-: From The President’s Epic, an article about the Republican statesman Abraham Lincoln (1809-1865), 16^th President of the USA from 1861 to 1865, published in The Press (Philadelphia, Pennsylvania) of Saturday 2^nd January 1864:

Friends and calumniators alike are assiduous in picking up incidents which they connect with him, and detail as biographic facts. They suggest that he commenced using the axe when he was very young. He has used it with wonderful effect ever since. He has wielded it with such a stalwart arm that he has chopped off the head of rebellion, and the animal is now jerking blindly around like a headless chicken in its last agonies.

3-: From Washington Letter, dated Saturday 9^th January 1869, published in The Cincinnati Commercial (Cincinnati, Ohio) of Wednesday 13^th January 1869—I have not discovered the meaning of “fetch the Cave of the Winds”:

Diplomatic Billy, who seems to have been possessed of a devil instigating him to purchase for the United States all the waste places and shaky islands outlying, and not worth much, has given us a complication in that of the proposed purchase of the Danish Islands. Poor Henry Winter Davis, the noblest spirit of them all, anticipated this very question, and insisted upon it that as the appropriations for the purchase money had to be voted for by the House, the House had a right to be consulted in the purchase. He could not, however, fetch the Cave of the Winds up to even a consideration of the question. Now it is forced upon us, and the Solons are jumping about like headless chickens.

4-: From Wanted—A Pastor, by ‘Laicus’, pen name of the U.S. Congregationalist minister Lyman Abbott (1835-1922), published in The New Covenant (Chicago, Illinois) of Saturday 26^th February 1870:

The church is without a head. It flounders about like a headless chicken; excuse the homely simile, which has nothing but truth to commend it.

5-: From Alfred the Great, a poem published in the Tama County Republican (Toledo, Iowa) of Thursday 28^th July 1870:

With disheveled hair, mothers flew round
Like headless chickens; children tumbled o’er
In fits, and howled and cried, as if by
Colic seized.

6-: From The Daily Journal of Commerce (Kansas City, Missouri) of Tuesday 26^th September 1871:

The “police authority” ran about the streets, like a headless chicken, laboring under a terrible attack of conscience. Men went round to saloons, free lunches, and other places of refreshment, with their parrot like lesson, shouting—“the Journal is going to close up the saloons, the barber shops, the beer gardens, the stores, the printing offices,” etc., all for—what? There was the rub—because it sustained the City Council in its action against the twin vices and the twin curses of our city.

7-: From the column City Jottings, published in The Salt Lake Daily Tribune (Salt Lake City, Utah) of Friday 24^th July 1874:

The Herald is floundering around like a headless chicken. It is now the weakest of the skim-milk Church organs, and is too insignificant to receive a square kick.

The noun headless chicken designates a person, group, etc., engaged in frantic but purposeless activity. The earliest occurrence of this noun that I have found is—as part of an extended metaphor—from The Norfolk Virginian (Norfolk, Virginia) of Thursday 7^th April 1870:

LET ’EM DANCE.

We are in daily expectation of further action on the part of the Chahoon-Underwood faction in this city, and the preposterous action of the Almshouse Committee foreshadows this. Well, let the chickens with their heads off enjoy the luxury of one last “ground hop.” Let us go on the even tenor of our way leaving them to flutter and flop and bounce and bound as long as they may be able to go through these mortuary performances. It would be cruel to interrupt their amusement, especially as they are dead chickens. Let them flutter unmolested, and in saying this we utter that which is of peculiar moment to this community. The party just hurled from power lives on agitation. That one word has been its magic spell to call up evil spirits ever since its organization, and they are now making a last, desperate effort to provoke a grand excitement. Let them reckon without their host. The law is in our favor and the Chief Justice will soon decide the question at issue. Let us, then, avoid all excitements. Let us exercise a wise moderation, and with a vigorous Mayor and reliable police force we can keep the peace beyond a peradventure. In the meantime if our headless chickens will have the Dance of Death, why, in heaven’s name, let them enjoy it, albeit no Holbien [sic*] will record their antics in imperishable cartoons.

* The German painter and engraver Hans Holbein (1497-1543) was a court portraitist in England.