In 1807 Calcraft was elected Member of Parliament for
Wareham, but resigned his seat at the close of 1808 on his regiment being ordered for service in the Iberian Peninsula. The 3rd Dragoon Guards were brigaded with the
4th Dragoons under the command of
Henry Fane, as the
Heavy Brigade, which was engaged in the
Battle of Talavera. General Fane fell ill, and Calcraft assumed the command of the Brigade, which he held until the arrival of
George de Grey in May 1810. The Brigade was frequently engaged during the retreat to
Torres Vedras, and again in the pursuit of General
André Masséna in March 1811. After the combat of Foz d'Aronce, the Heavy Brigade served on the left bank of the
Tagus under
Marshal Beresford. Calcraft, who had been promoted colonel for his services on 25 July 1810, was engaged at the head of his regiment at the
Battle of Campo Maior, at the
Battle of Albuera, and in
William Lumley's charge at Los Santos on 16 April 1811. In January 1812 the Heavy Brigade, which was again temporarily under the command of Calcraft, assisted in covering the
siege of Ciudad Rodrigo, and when Wellington formed the
Siege of Badajoz, it was left with
General Graham's division to watch
Auguste Marmont. After the
Battle of Salamanca the cavalry division was in the action at Llera on 11 June 1812, when General
Charles Lallemand's cavalry was cut to pieces, and Calcraft was mentioned in
General Slade's report. The Brigade was then engaged in covering
Rowland Hill's retreat from Madrid, and in December 1812 Calcraft was made a knight of the Portuguese
Order of the Tower and Sword for his services. On 4 June 1813 he was promoted major-general, and left the Peninsula theatre. ==Later life==