one fell swoop

After Shakespeare, in Macbeth, act iv, scene 3, where Macduff learns his wife and entire family are murdered:

Ro. Wife, Children, Servants, all that could be found. […]

Macd. […] All my pretty ones?
Did you say All? Oh Hell-Kite! All?
What, All my pretty Chickens, and their Damme
At one fell swoope?

The imagery is of a bird of prey ("hell-kite") ransacking a whole nest at one blow, fell meaning "terrible, cruel, savage." In later uses of the expression, the force of the metaphor is reduced or lost.

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one fell swoop

1. (idiomatic) One stroke; one action or event that achieves or accomplishes many results.

   Changing the oil lubricates the engine and removes debris in one fell swoop.

   • 1922 February, James Joyce, Ulysses, Paris: Shakespeare and Company, […], →OCLC:
     , Episode 16:

     ...they might be hanging about there or simply marauders ready to decamp with whatever boodle they could in one fell swoop at a moment's notice, your money or your life, leaving you there to point a moral, gagged and garrotted.

   • 1955 June, Robert F. Legget, “Dieselisation of Canadian Railways”, in Railway Magazine, page 417:

     There can be few examples in the history of railways of a reduction of sixteen hours in the running time of one train, at one fell swoop, but this has been achieved by the Canadian Pacific Railway with its transcontinental train service, an advance without any parallel in the record of Canada's railways, and the first major timetable change of any sort for several decades.

   • 2023 July 26, Pip Dunn, “Merseyrail '777s' are OK for commuters”, in RAIL, number 988, page 59:

     Remember that these trains will serve Aintree on race days and both Anfield and Goodison Park (and soon Everton FC's new stadium), so there will be times when they are packed to the gunwales with passengers - albeit, disgorging their footfall at one station in one fell swoop.

• Gordian knot
• swoop
• at one stroke
• kill two birds with one stone
• in one foul swoop

• one swell foop