Lieutenant General Sir Colin Campbell (1792-1863), commander of the 'Thin Red Line' (Roger Fenton, 1855).
The Thin Red Line is a term for a thinly spread military unit holding firm against attack. The phrase later took on the metaphorical meaning of the barrier which the relatively limited armed forces of a country present to potential attackers. The first use of the expression referred to the resistance by the red-coated 93rd Highland Regiment of the UK in the Crimean War.
The Thin Red Line, painted by Robert Gibb.
The Thin Red Line was a famous military action by the British Army's red-coated Highland Brigade, at the Battle of Balaclava on October 25, 1854. The brigade and its leader distinguished themselves very greatly: with his 'thin red line of Highlanders' he repulsed the Russian attack, and prevented the Russions from occupying Balaklava.