"like Mr Bayes's troops, and march off"

The Rehearsal was a satirical play aimed at John Dryden, and specifically Dryden’s exhortations in favour of ‘heroic drama.’ It was published anonymously, and staged in 1671.  Evidence suggests that it was by George Villiers, 2nd Duke of Buckingham, and several collaborators.

The play concerns a playwright named Bayes attempting to stage a play, which is made up almost entirely of excerpts of existing heroic dramas.  Most of these excerpts are lifted from Dryden, including his very popular The Conquest of Granada

In Dryden’s preface to The Conquest, he had scolded other dramatists for having immoral heroes and low sentiments, and proposed heroic drama as a new type of theater. The Rehearsal takes heroic phrases and speeches from Dryden's play and pastes them haphazardly together, exposing their over-blown absurdity.

In December 1742, the following advert appeared for The Rehearsal:

“Mr Bayes’ Troops have been on their March for some Days past from their late Encampment in Goodman’s Fields; they march’d in good Order through the City without Beat of Drums, and were received at Lincoln’s Inn Fields, where they have now pitch’d their Tents with great Acclamations of Joy by the Populace.  We hear they will be reinforced by some Auxiliaries from Covent-Garden; and we can assure the Publick, there will certainly be a Battle of Monday next, so the Report of their going quietly into Winter Quarters without coming to Action, proves a groundless Tale, and was merely calculated to serve some private Ends.”