The Shakespeare mania culminated in Ireland's impudent but clever forgeries, which deceived many learned and acute critics of the day; and when Ireland prevailed upon Sheridan to produce Vortigern at Drury Lane, in 1796, Mr. Pye wrote a prologue to the tragedy, but as it expressed a doubt about the authenticity, it was laid aside to make place for one written by Sir James Bland Burgess. This commenced with a bold assertion that the piece about to be performed was the work of Shakespeare, and demanded the respectful attention of the audience to it on that account.
The piece utterly broke down the first night, and when the imposition was discovered, there were some bitter caricatures and satires published at Ireland's expense; one of these was a portrait of the forger, grasping a volume of Shakespeare, with a motto, taken from the Maid of the Mill:—
Such cursed assurance
Is past all endurance,
and the following parody of Dryden's Epigram on Milton, supposed to have been written by William Mason:—
Four forgers, born in one prolific age,
Much critical acumen did engage;
The first was soon by Doughty Douglas scar'd,
Tho' Johnson would have screen'd him had he dar'd.
The next had all the cunning of a Scot
The third invention, genius — nay, what not?
Fraud now exhausted, only could dispense
To her fourth son, their threefold impudence.
It is said that Ireland was so enraged at the publication of this caricature, that he broke the shop windows where it was exposed for sale.
After Vortigern and Rowena had been once played, and the audience had shown in the most unmistakable manner their disbelief in its authenticity, and contempt for its merits, Ireland yet had the audacity to urge Sheridan and Kemble to have a second performance, but Sheridan dismissed him with a very emphatic negative. After Ireland had left the room, Kemble said, "Well, sir, you cannot now doubt that the play is a forgery." "Damn the fellow replied Sheridan, "I believe his face is a forgery; he is the most specious man I ever saw!"
Ireland afterwards wrote a book, admitting that he was the author of Vortigern and other imitations of Shakespeare with which he had deceived many literary men, and describing in a bold, almost exulting tone, the numerous ingenious devices he adopted to carry out the deception, particularly in the selection of ink, paper, writing, and orthography, to resemble old manuscripts.