A new BBC documentary has re-examined the legacy of a controversial Scottish soldier who was dubbed "Mad Mitch" for his tough methods.
Lt Col Colin Mitchell became a national hero when he led his Argyll and Sutherland Highlanders back into the Crater area of Aden in July 1967.
The British army had earlier pulled out of the district after 24 soldiers were killed by insurgents.
But Mitchell's reputation has been tarnished by allegations of brutality.
Aden, in what is now Yemen, had for more than 100 years been Britain's only Arab colony - but its rule was coming to an end amid an armed uprising by nationalists.
Scottish regiments were sent to keep the peace in what became known as the Aden Emergency.
In the summer of 1967 the local police mutinied and killed 24 British troops, including three Argylls. The bodies of the dead soldiers were dragged through the streets and mutilated.
Mitchell was horrified by the decision to withdraw British forces from Crater as a result of the killings, and by the failure of the army to recover the bodies of the dead soldiers, which he viewed as a betrayal of those who had died.
On the night of 3 July 1967, while senior officers wanted to negotiate a peaceful return to the area, Mitchell and his men, accompanied by 15 regimental pipers blaring out Scotland the Brave, reoccupied the Crater.
The district of about 80,000 people was retaken with hardly a shot fired.
Mitchell, who always considered himself Scottish despite being born and raised in London, later used his controversial concept of Argyll Law to maintain order.
The strong arm tactics endeared the brusque Mitchell to the British media and public and were credited with helping to avoid the security breakdown that was happening elsewhere in Aden.
Allegations of abuse
But it did little to endear him to the local population in Crater - or to his superiors in the army and High Commission, with one official describing the Argylls as a "bunch of Glasgow thugs."
Labour MP Tam Dalyell asked in parliament whether Mitchell had disobeyed orders by re-entering Crater.
Allegations of abuse and mistreatment soon followed.
Leading Yemeni lawyer Sheik Tariq Abdullah recalled: "They [The Argylls] were very rough. They tried to show as much restraint as possible but in general during that period you would find most of the people complaining."
But Mitchell firmly believed Argyll Law was the only way of tackling the insurgents, who left 200 British soldiers dead across Aden.
He said at the time: "I have no compunction in saying that if some chap starts throwing grenades or starts using pistols, we shall kill him."
Speaking a few years before his death in 1996, Mitchell remained unapologetic.
"A great many Arabs are alive today because we used these methods and a great many Argylls are alive today because we used them," he said.
"This to me is the complete exoneration of anything, if we needed exonerating, which we don't and never have done."
By the time the British withdrew completely from Aden in November 1967, Mitchell had clashed with the army high command once too often.
On his return home to Britain, it was made clear there was no room in the military for Mad Mitch.
He resigned from the army in 1968, before taking up a prominent role in the Save the Argylls campaign and eventually winning the Aberdeenshire West seat in parliament for the Conservatives in the 1970 General Election.
But his brief career as a politician last only four years, and was dogged by his frequent criticism of the army top brass.
He became involved in a failed business venture before the next 10 years were spent in unsuccessful attempts to get back into Parliament, with the one-time darling of the British public finding himself an increasingly marginalised figure.
His final years saw him take on a leading role with the Halo Trust, a non-profit organisation which removed mines from former war zones.
Maj Alastair Howman, who served alongside Mitchell in Aden, said the Argylls had nothing to apologise for on the 40th anniversary of their withdrawal.
The end of British rule left a power vacuum which resulted in the deaths of thousands of people in the decades of civil war that resulted.
But Maj Howman accused today's politicians of failing to learn the lessons of the Aden Emergency.
He said: "Crater was run on Argyll Law and that is perfectly sensible because there wasn't any other law.
"Once somebody declares what date they are going leave a situation it is fraught with danger for the people who are there.
"That happened in Aden and it seems to certainly be happening in Iraq. I don't think politicians ever really learn this lesson. I don't think they read their history books."
Mad Mitch and The Last Battle of the British Empire was broadcast on BBC 2 Scotland on 26 November at 2000 GMT.