The verb to frog-march (somebody) means to force (somebody) to walk forward by holding and pinning their arms from behind.

This sense is milder than the original, as the frog’s march was a police metaphor denoting a method of moving a resistant person such as a prisoner, in which he or she is lifted by the arms and legs and carried in a prone position with the face pointing towards the ground.

The Edinburgh Evening News (Edinburgh, Lothian, Scotland) of Friday 13th March 1874 described—and condemned—this method:

THE LONDON POLICE AND THE “FROG’S MARCH”.

The objectionable practice which prevails among the police of occasionally carrying prisoners to police stations by a process known as the “frog’s march,” or, in other words, with the face downwards and the whole weight of the body dependent on the limbs, has so often called forth severe remarks, and has done so much to embitter the relations between the “police and the public” that it is to be regretted they still adopt a proceeding as barbarous as it is uncalled for. At the Marlborough Street Police Court on Monday a man named William Harrod was charged with drunkenness and disorderly conduct on Sunday night, and he seems fully to have deserved the penalty imposed upon him of sixty shillings, or a month’s imprisonment, for his violent conduct, but on the other hand the treatment he received from the police appears, to say the least, barbarous. According to the evidence of one constable, the prisoner, on being taken into custody, “became so violent that they (the police) had to lay him down and sit upon him.” Another constable deposed that he “knelt” on the prisoner, but did not himself make use of him as a seat. Harrod complained that he had been treated very roughly, and had had the “frog’s march” given him. The magistrate “could not see why four constables could not have taken the man to the station without kneeling or sitting on him, and expressed his disapproval of such proceedings. If they could not have carried the man, they should,” he added, “have sent for the stretcher.” It is altogether a disagreeable story, and shows that police education is yet very far from complete.

On Saturday 6th April 1889, The Illustrated Police News (London, England) published the following picture, and its explanation:

DEATH FROM THE “FROG’S MARCH.” EAST END.

ALLEGED DEATH FROM THE “FROG’S MARCH.”

On Tuesday Dr. Macdonald, the coroner for North-east Middlesex, held an inquest at the Shoreditch Town Hall on the body of Samuel Mahoney, a labourer, aged twenty-six, of Boundary-street, Shoreditch, who was supposed to have died in consequence of being taken by the police to the lock-up in the mode known as the “frog’s march.” Evidence was given that the deceased was taken into custody for disorderly conduct. He was very violent, and to prevent his struggling the police carried him to the station face downwards. On arrival they found he was dead. Doctor George Bagster Phillips, of No. 2, Spital-square, and divisional surgeon of police, deposed that he was called to Commercial-street Police-station, where he found the deceased lying on his back dead. The features were calm and there were no marks of violence apparent. A post-mortem examination had since been made, and the cause of death ascertained to be syncope, due to disease of the lungs and the violent exercise the man had gone through. While returning a verdict of death from syncope, consequent on the excitement of the struggle, the jury desired to add that the ambulance should have been used in this case and in all future cases of similar description, and also that independent medical testimony should be secured, and not the divisional surgeon’s, the “frog’s march” to be discontinued.

The earliest instance of the frog’s march that I have found is from The Kilkenny Journal, and Leinster Commercial and Literary Advertiser (Kilkenny, County Kilkenny, Ireland) of Wednesday 11th September 1867:

MAYOR’S OFFICE.—Monday.
(Before the Right Worshipful John Buggy, Mayor.)

A Would-be Rowdy.—A young gent, styling himself —— —— and hailing from the neighbourhood of Abbeyleix, was brought before the Mayor charged with having on Sunday evening, at the Waterford and Kilkenny Railway platform violently assaulted police-constable Kenny, and obstructing him in the discharge of his duty.
It appears that defendant was on the platform on the previous evening apparently under the influence of drink, when he commenced jostling against the respectable citizens who were proceeding on the platform, until he had to be removed by the Railway officials. Constable Kenny on advising him to keep himself quiet was knocked down and severely assaulted by him. He was then arrested, but resisted so violently that he had to get the “frog’s march” to the police barrack, where the “darbys” were placed on him, and he was conveyed in all state to the lock up several youngsters preceeding him and singing “Johnny I hardly knew you.”
Head Constable McLoughlin said it was a most disgraceful scene there were over 200 persons present.
The Mayor said he was at first inclined to send the case to Petty Sessions, but as the police did not wish to press the charge he would impose a penalty of 5s. The fine was paid.

The verb to frog-march soon appeared. The earliest occurrence that I have found is from The Dover Express and East Kent Intelligencer (Dover, Kent, England) of Friday 12th July 1872. This newspaper reported that a soldier of the 67th Regiment threw himself over a cliff, apparently with the intention of committing suicide; a police officer happening to be near the spot raised him to the top:

He [= the soldier] lay for a short time insensible, but on coming to be again attempted to throw himself over the cliff, and was only kept back by the police-officer. A picquet coming up, he was handed over to their charge, but was so unruly that he was “frog-marched” to the old station-house in High Street.

The following paragraph is from The Cardiff Times (Cardiff, Glamorgan, Wales) of Saturday 20th June 1885:

Upon a woman being charged at Cardiff, a few days ago, with being drunk and disorderly, evidence was given by one or two gentlemen that the police had “frog-marched” her to the station. Frog-marching is a barbarous process enough when applied to a strong man, as we know from what happened not long ago at Walmer*; but applied to a woman it is grossly indecent, as well as cruel, as was proved in this very case.

* This refers to a private in the Royal Marines, named Ault, who died in November 1884 from suffocation produced by being frog-marched from Deal to Walmer, in Kent.