When Alexander was sixteen, he crushed the Maedi insurgence, conquered their home territory and founded a city. he then went on to subdue revolts in Thrace, taking the city of Perinthus. He repelled an Illyrian invasion of Macedon. At eighteen he marched his army through Thermopylae and broke the Theban lines at the battle of Chaeronea and occupied the Peloponnese. At twenty he was proclaimed King of Macedon. A year later he defeated the Thracians and took his army to the banks of the Danube. At twenty-two he crossed the Hellespont and defeated the Persian Empire, and went on to take Syria and most of the Levantine coast. Then he conquered Egypt before he was twenty-four
Slightly more recently, at the age of twenty-four Captain Frederick Browning was commanding an infantry Company, having won both the DSO and the Croix de Guerre in the trenches in 1917 three years before.
More recently still, Brummie teenager Private Kennedy, 18, became the youngest holder of the Military Cross for displaying selfless bravery and a cool head under heavy Taliban attack.
None of them would have escaped the mandatory requirements of the new Alcohol Etc (Scotland) Act 2010. This requires bar and club staff to challenge each and every customer who looks younger than 25 and all those so challenged must provide satisfactory ID before they can be served with alcohol.
So if you encounter a battle-grizzled and be-medalled RRS sergeant of 24 hanging about outside the Calvin Arms on Leith Walk, spare him your time. He'll only want you to buy a pint of lager for him.