As tensions mounted, Slanning used his position in Falmouth to import military supplies for the Royalist cause. When the
First English Civil War broke out in August 1642, he began raising troops in Cornwall. He, Grenville,
William Godolphin, Trevanion and
Warwick Mohun recruited five regiments collectively known as "the Tinners", since many came from local tin mines controlled by Slanning and Godolphin. Although regarded as some of the best infantry available to the Royalists, the rank and file often had little choice in deciding whether to "volunteer"; Grenville, generally regarded as a benevolent landlord, threatened his tenants and employees with sanctions if they refused to sign up. In addition, while militia on both sides often refused to serve outside their own counties, the Cornish were particularly noted for their reluctance to serve outside Cornwall or under non-Cornish officers, factors which later limited their usefulness. In October, Slanning relinquished his position as Governor of Pendennis and joined the field army assembled by
Sir Ralph Hopton for an unsuccessful attack on
Exeter. After victory at
Braddock Down in January 1643, Hopton moved against
Plymouth but many of the Cornish troops refused to cross the
River Tamar into Devon. The Royalists were very short of basic supplies like gunpowder and ammunition and on 21 February were routed by
Parliamentarian troops at
Modbury; Slanning's regiment suffered over 350 killed, wounded or captured. The two sides agreed a local truce, an agreement greeted with incredulity by
William Waller, Parliamentarian commander in the West. Hopton used the opportunity to reorganise his army, while Slanning brought his unit back up to full strength and they resumed the offensive after the truce ended in April. Although repulsed at
Sourton Down on 25 April, the Royalists won a resounding victory at
Stratton on 16 May, Slanning and Trevanion commanding the left flank of their attack. Having linked up with
Prince Maurice, they advanced into
Somerset and defeated Waller first at
Landsdowne on 5 July, then
Roundway Down eight days later. These victories ensured Royalist control of
South West England but the Cornish foot suffered heavy casualties, including Grenville who was killed at Lansdowne. Recognising an opportunity to capture
Bristol, then the second-largest port in England,
Prince Rupert left
Oxford and on 23 July met up with Prince Maurice and the Western Army outside the city. Early on the morning of 26 July,
simultaneous attacks were made by Prince Rupert's men in the north while Prince Maurice assaulted the stronger southern defences. Although the northern attack was successful, the Cornish were repulsed three times and lost over 200 combatants, including many senior officers. Trevanion died of his wounds the same night, Slanning "had his thigh broken with a case shot, whereof he dyed three weeks later". ==References==