The phrase alarums and excursions, also alarms and excursions, denotes confused activity and uproar.

The noun alarum is an archaic form of alarm, meaning a call to arms (the vowel between -r- and -m- in alarum perhaps arose from rolling of the -r- in the final syllable of the call).

The noun excursion denotes a sortie, i.e. an attack made by troops coming out from a position of defence.

The phrase alarums and excursions is an allusion to the frequent collocation of the words alarum (also occasionally alarm) and excursion in stage directions in battle scenes in a number of plays by the English poet and dramatist William Shakespeare (1564-1616)—although neither alarums and excursions nor alarms and excursions appear in Shakespeare’s plays.

For example, the stage directions are as follows at the beginning of Act V, scene 3, of The history of Henrie the fourth [Part 1] (Quarto 1, 1598):

Alarme, excursions. Enter the King, the Prince, Lord Iohn of Lancaster, Earle of Westmerland.

But, at the beginning of Act V, scene 3, of The First Part of Henry the Fourth (Folio 1, 1623), the stage directions are:

Alarum, excursions, enter the King, the Prince, Lord Iohn of Lancaster, and Earle of Westmerland.

The phrase is first recorded—in its military acceptation and in the form alarms and excursions—in The Siege against Lathom House in the year 1643, published in The European Magazine, and London Review (London, England) of February 1793. This text was presented as the transcription of a handwritten diary of the siege of the Royalist stronghold of Lathom House, in Lancashire, by a Parliamentarian army during the English Civil War (1642-49):

21st, 22d, 23d, and 24th. The four following days were spent in alarms and excursions without much business of service.

The earliest instance of the phrase that I have found is from an article published in The Waterford Mail (Waterford, County Waterford, Ireland) of Wednesday 17^th February 1830; the author likens to a Shakespearean drama the political scheming in the designation of the candidate in a legislative election:

Thus ends Act the Second.
The third and concluding portion of the drama opens with confusion, and ends, like Shakespeare’s Historical Tragedies, with “Alarms and Excursions.”

The second-earliest occurrence of the phrase that I have found appears in a military context; it is from The Northern Whig (Belfast, County Antrim, Ireland) of Saturday 14^th September 1839:

The War in Spain.—Foreign Policy of the Present Ministry.—The Spanish war is nearly at an end. That contest, which has existed for several years, with various success—which has desolated several of the finest provinces of Spain—impoverished her people—spilled, like water, the blood of thousands of her children, has come to a close,—more from mere exhaustion, on the part of the combatants, than from any great or decided advantage gained by one side over the other. It has been a remarkable feature of this civil war, that scarcely any thing approaching to a pitched battle or a regular siege has taken place. We have had “alarums and excursions,” surprises, desolations, massacres, and butcheries of prisoners, in multitudes; but little or nothing of what we may term war on a grand scale.

I have found another early instance of the phrase in the following from The Morning Chronicle (London, England) of Saturday 7^th April 1849:

Autres temps, autres mœurs*. It is clear that the spirit of the gallant Lord George no longer prevails in the Protectionist councils. No more storming of windmills—no more challenging of recumbent lions—no more adventurous descents into the bottomless pit of statistics. The good knight, vowed to the immaculate reputation of Mr. Canning, has disappeared, and with him the policy of alarms and excursions. A Protectionist campaign is now an affair as stately as a minuet.

* The French phrase autres temps, autres mœurs, literally other times, other customs, is a translation of the Latin o tempora o mores, literally oh the times oh the customs, used by the Roman statesman, orator and author Marcus Tullius Cicero (106-43 BC) in First Oration against Catiline (Oratio in Catilinam Prima), in which Cicero accused Lucius Sergius Catilina (circa 108-62 BC) of leading a plot to overthrow the Roman government.