[4] A squadron under Captain de Rabaudy, comprising the 60-gun frigate Melpomène[8] and the 20-gun brig Endymion, under Nonay, was sent to the mouth of the Tagus river to show the flag and give weight to the demands of the French consul.

[10] Upon her departure from Brest, Melpomène ran aground on Basse Beuzec, and had to double back, leaving Endymion to continue her route.

In consequence, Rabaudy's Melpomène started blockading Lisbon by preying upon shipping leaving and entering the Tagus, though their crew were immediately freed and sent ashore.

Departed from Brest, the squadron arrived off the Tagus on 25 June, and stayed there waiting for the division inbound from Toulon, under Rear-admiral Hugon.

[17] The new ultimatum comprised the same condition as the first, but added that the Portuguese government should compensate France for the price of the naval expedition, and threatened of a "de facto war".

The French squadron sailed one by one in front of the forts, delivering broadsides at distances varying from 100 to 1000 metres, and reached Paço de Arcos in good order and with no serious damage.

[25] The Portuguese government caved in, and a treaty was signed on 14 July on Suffren by Castello Branco and Roussin,[1] with its dispositions published in the Lisbon Gazette on 15,[26] and the sums of money begin paid in cash by the 23.

[27] With the ultimatum accepted by the Portuguese, Roussin sent most of the squadron to sea, staying in front of Lisbon with only Suffren, Pallas and Melpomène; the 58-gun frigate Guerrière, under Captain Kerdrain, rejoined him on 29.

[23] Key The treaty of 14 July specified that the French would return the ships captured before the attack on the Tagus, including the warships Orestes and Urania and the merchantmen with their cargo.

[33][34] After a council of war on Trident, the French decided to also return the captured 74-gun Dom João VI as, being neither armed nor manned during the action, she did not belong to an opposing force.

[21][28] The Miguelists would suffer a crushing defeat at the hands of the Liberals at the Battle of Cape St. Vincent two years later, ending the reign of Miguel I.