Squire was promoted to be captain lieutenant in February 1803, and second captain on 19 July 1804. He was employed in the southern military district on the defences of the coast of Sussex. On 1 July 1806 he was promoted to be first captain, and appointed commanding royal engineer in the expedition to South America. He accompanied
Sir Samuel Auchmuty to the
Río de la Plata, landing in January 1807. Squire conducted the siege operations at
Montevideo: after a practicable breach was made, it was carried by storm on 3 February. He was also commanding Royal Engineer under Major-general
John Whitelocke in the operations from 28 June to 5 July. It culminated in the attack on
Buenos Aires and the surrender of Montevideo, and the expedition returned to England. Squire was a witness for the prosecution at the court-martial held in London in March 1808. In April 1808 Squire accompanied
Sir John Moore's expedition to Sweden, and in the summer went with Moore's army to
Lisbon, taking part in all the operations of the campaign, which ended on 16 January 1809 in the
Battle of Coruña. He embarked the same night with the army for England, arriving in February. In April he was sent by
Lord Castlereagh in a frigate on a secret mission to the
Baltic Sea, to report on the island of
Bornholm as a defensive naval station. On 28 July of the same year, Squire took part in the
Walcheren Campaign. He sailed, as commanding Royal Engineer to
Sir John Hope's division, with the army under the
Earl of Chatham to the
River Scheldt. On 30 July he reconnoitred the channel and shores of the East Scheldt with Captain Peake, R.N.. He took part in the siege of
Vlissingen, and was present at its capture on 14 August, returning to England in December. ==Peninsular War and death==