The phrase to get one’s wires crossed means to misunderstand.
It alludes to an accidental connexion between telephone or telegraph wires of different lines or circuits. This was mentioned in My Newspaper, published in All the Year Round. A Weekly Journal. Conducted by Charles Dickens1 (London, England) of 25th June 1864—the narrator gives an account of his visit to the offices of a London newspaper:
I proceeded to a suite of rooms occupied by the sub-editor and the principal reporters. In the outermost of these rooms is arranged the electric telegraph apparatus, three round discs with finger-stops sticking out from them like concertina-keys, and a needle pointing to alphabetic letters on the surface of the dial. One of these dials corresponds with the House of Commons, another with Mr. Reuter’s telegraph office, the third with the private residence of the proprietor of my journal: who is thus made acquainted with any important news which may transpire before he arrives at, or after he leaves, the office. The electric telegraph, an enormous boon to all newspaper men, is specially beneficial to the sub-editor; by its aid he can place before the expectant leader-writer the summary of the great speech in a debate, or the momentous telegram which is to furnish the theme for triumphant jubilee or virtuous indignation; by its aid he can “make up” the paper, that is, see exactly how much composed matter will have to be left “standing over,” for the tinkling of the bell announces a message from the head of the reporting staff in the House, to the effect, “House up—half a col to come.” Sometimes, very rarely, wires get crossed, or otherwise out of gear, and strange messages relating to misdelivered firkins of butter, or marital excuses for not coming home to dinner, arrive at the office of my journal. The sub-editor has a story how, after having twice given the signal to a West-end office which Mr. Reuter then had, he received a pathetic remonstrance from some evidently recently awakened maiden, “Please not to ring again till I slip on my gown!”
1 Charles Dickens (1812-70), English novelist
A text containing an early occurrence of the phrase to get one’s wires crossed explicitly alludes to an accidental connexion; it is from The St. Joseph Herald (St. Joseph, Missouri) of Wednesday 30th December 1891:
An Angry Bridegroom.
Edward T. Cook, colored, who was was [sic] married yesterday afternoon to Miss Hattie Snowden, called at The Herald office last night and and [sic] entered a general denial of the charges made against him in an evening paper. He said that he married the young lady because he loved her and not for the reason that he was compelled to as stated.
He got his wires crossed, “telephonically” speaking, and applied at the Central police station for a marriage license, but an about-to-be-married man has done queer things under the excitement of the moment. Mr. Cook was directed to the proper office at which to apply for a license and made no further mistakes.
The earliest instance of to get one’s wires crossed that I have found is from the Daily Illinois State Register (Springfield, Illinois) of Wednesday 17th July 1878:
Old Probs2 announced, yesterday morning that a decided fall in temperature was entering the United Sates from Manitoba. A precursory examination, however, convinced the average citizen that the old man had got his wires crossed and the change of temperature came from the place Bob Ingersoll3 says exists not.
2 Cleveland Abbe (1838-1916), nicknamed Old Probabilities, or, for short, Old Probs, was the chief meteorologist at the United States Weather Bureau.
3 Robert Green Ingersoll (1833-99) was an American author and orator; I have not found what “the place Bob Ingersoll says exists not” alludes to in his writings.
The second-earliest occurrence of the phrase that I have found is from the column Passing Events, in The Cleveland Leader (Cleveland, Ohio) of Wednesday 21st May 1879:
“We join the Democrats of the North,” said Ben Hill4 in his speech, “because we admired their course during the war.” Of course you do, Mr. Hill. You never was a Democrat or had any sympathy or affiliation with that party, until it allied itself to the rebel cause “during the war.” But when you go on to assert, as you do, that it was “not the Republicans, but the Northern Democrats, who saved the Union,” you not only deny what is history, but expose your own inconsistency, in “admiring” the Northern Democrats for doing what you undertook by war to prevent. You get your “wires crossed,” Mr. Hill.—Blade.
4 Although he had opposed the Secession, Benjamin Harvey Hill (1823-82) served as a Confederate senator representing Georgia (1861-65). After the American Civil War (1861-65), he became a Democrat, was elected to the U.S. House of Representatives (1875-77) and to the U.S. Senate (from 1877 until his death).