Lawrence was a son-in-law of William Fairfax, proprietor of the neighbouring plantation of Belvoir, and agent for the extensive Fairfax lands in the colony.
Lawrence had served with Fairfax at Cartagena, and had made the acquaintance of Admiral Edward Vernon, from whom Mount Vernon was named.
He took Devizes and Laycock House, Winchester and Basing House, and rejoined Fairfax in October at Exeter, and accompanied him to Cornwall, where he assisted in the defeat of Hopton's forces and in the suppression of the royalists in the west.
He urged Fairfax to attack the Scots at once in their own country and to forestall their The invasion; but Fairfax refused and resigned, and battles of Cromwell was appointed by parliament, on the 26th Dunbar of June 1650, commander-in-chief of all the forces and of the Commonwealth.
On the 28th he was sent to Ely for the defence of the eastern counties against the king's advance; and on the 10th of June, upon Fairfax's petition, he was named by the Commons lieutenant-general, joining Fairfax on the 13th with six hundred horse.
During the Civil War General Goring quartered his troops at Totnes, and Fairfax also made it his temporary station.
On the 9th of January 1646 he surprised Lord Wentworth's brigade at Bovey Tracey, and was present with Fairfax at the fall of Exeter on the 9th of April.
The lords and the Scots vehemently took Manchester's part; but the Commons eventually sided with Cromwell, appointed Sir Thomas Fairfax general of the New Model Army, and passed two self-denying ordinances, the second of which, ordering all members of both houses to lay down their commissions within forty days, was accepted by the lords on the 3rd of April 1645.
On the other side the cavalry of the Eastern Association under Lieut.-General Cromwell and that of the Scots under Major-General Leslie (Lord Newark) formed the left, the infantry of the Eastern Association under Major-General Crawford, of the Scots under Lord Leven, and of the Yorkshire Parliamentarians under Lord Fairfax was in the centre and the Yorkshire cavalry under Sir Thomas Fairfax was on the right wing.
General Fairfax and General Lambert are mentioned as occupants after his death, and later the property was let, William Penn of Pennsylvania being among those who leased it.