The informal British phrase to chance one’s arm means to undertake something although it may be dangerous or unsuccessful.
Its origin is unclear. The earliest use that I have found is from How our blue-jackets are fed, an article about the “diet of the British sailor at sea” published in The Weekly Telegraph (Sheffield, Yorkshire) of Saturday 7th September 1889:
Jack cannot, in nine ships out of ten, cook himself a herring for breakfast or tea without laying himself open to punishment; “chancing his arm,” is the naval term.
The following letter, published in The Daily News (London) of Monday 13th November 1899, seems to confirm that the phrase originated in forces’ slang. The correspondent apparently alludes to a comedian impersonating Robert Baden-Powell (1857-1941), English soldier and founder of the Boy Scout movement, who became a national hero as a result of his successful defence of Mafeking from October 1899 to May 1900 in the Boer War:
“Colonel Baden-Powell,” writes a correspondent, “is a bit of a philologist, though I cannot at all times agree with him. In his musical sketches he illustrates his interpretation of the phrase, ‘to chance your arm,’ which means, whether it be slang, or whether it be classical, ‘to risk it,’ or ‘to have a try, just for luck.’ When B. P. is mimicking a non-commissioned officer, he always keeps the elbow extended, so as to show prominently all the badges of rank. B. P. says to ‘chance your arm’ means to risk a court-martial which has the power to take all the pretty pretties off a man’s sleeve. I first heard the phrase in 1886, but an old soldier tells me it is quite twenty-five years old. Then again, it may be classical. Perhaps some of your readers can assist.”
It seems therefore that, among sailors and soldiers, to chance an arm meant to take a chance—to break regulations for example—that might lead to punishment, demotion and the consequent loss of one’s stripes of rank, worn on the arm. According to B. A. Phythian in A Concise Dictionary of Phrase and Fable (1993):
It may have entered army slang from an earlier use in boxing circles, where it meant exposing oneself to risk by extending one’s arm in a punch, leaving part of the body undefended.
But a different explanation appeared in The Daily News on Thursday 16th November 1899, in response to the above-mentioned letter:
In reference to our paragraph on Colonel Baden-Powell and the slang term, to “chance your arm,” “allow me,” says an old tailor, “to acquaint your correspondent of the fact that it is a tailor’s phrase, and used by him in the same sense as Colonel Baden-Powell uses it. For instance, if a tailor had made a job which he himself was not sure would pass the cutter, he would say, ‘I will take it down, and chance my arm,’ or chance his luck. The phrase is much older than either your correspondent or Colonel Baden-Powell, and no doubt crept into the Army through the Master Tailor. We tailors would say of Colonel Baden-Powell, when he makes his sorties out of Mafeking, that he chances his arm, and that if he came out of the scrimmage without much loss, he had a bit of sutt (i.e., luck). We hope that he will keep on ‘chancing his arm,’ and come out of it with a bit of ‘sutt.’”
In A Dictionary of Slang, Jargon and Cant (Edinburgh, 1889), Albert Barrère and Charles Godfrey Leland had also written that the phrase originated in tailors’ slang:
Chance your arm (tailors), try, let it go, chance it.
If the following origin, published on the website of Saint Patrick’s Cathedral, Dublin, were true, instances of to chance one’s arm would most probably have been recorded between the date of the feud in question and the late 19th century:
In 1492 two Irish families, the Butlers of Ormonde and the FitzGeralds of Kildare, were involved in a bitter feud. This disagreement centred around the position of Lord Deputy. Both families wanted one of their own to hold the position. In 1492 this tension broke into outright warfare and a small skirmish occurred between the two families just outside the city walls. The Butlers, realising that the fighting was getting out of control, took refuge in the Chapter House of Saint Patrick’s Cathedral. The FitzGeralds followed them into the Cathedral and asked them to come out and make peace. The Butlers, afraid that if they did so they would be slaughtered, refused. As a gesture of good faith the head of the Kildare family, Gerald FitzGerald, ordered that a hole be cut in the door. He then thrust his arm through the door and offered his hand in peace to those on the other side. Upon seeing that FitzGerald was willing to risk his arm by putting it through the door the Butlers reasoned that he was serious in his intention. They shook hands through the door, the Butlers emerged from the Chapter House and the two families made peace. Today this door is known as the “Door of Reconciliation” and is on display in the Cathedral’s north transept. This story also lives on in a famous expression in Ireland “To chance your arm”.
A.D. 1492—The reconciliation of the Earls of Kildare and Ormond, in St Patrick’s Cathedral — image: Saint Patrick’s Cathedral