A young arab boy, armed with a rifle and a knife, in the Aden Protectorate near Yemen. (Photo by Richards/Fox Photos/Getty Images). February 1938

A Yemeni tribesman. (Photo by General Photographic Agency/Getty Images). Circa 1935

Tribesmen of the Aden Protectorate who are being trained on British Military lines are issued with rifles. (Photo by Fox Photos/Getty Images). Circa 1938

Armed members of the Yemeni National Liberation Front, who forced the British to withdraw, in 1967. The federation became independent as the People's Democratic Republic of Southern Yemen. (Photo by Three Lions/Getty Images). Circa 1950

The Federal Army in a camp in Dhala, Aden. (Photo by Fox Photos/Getty Images). 1962

Yemeni tribesmen at war with the British. (Photo by Bert Hardy/Picture Post/Getty Images). 11th February 1957

Camel races at Aden organised by the Khormaksar Club. (Photo by William Vanderson/Fox Photos/Getty Images). May 1959

The Governor of Qataba and the Sheik of the Shueib tribe (from Dhala) stand on the roof of the Government Guest House at Qataba (500 yards from the Aden Protectorate frontier), with a collection of weapons. (Photo by Topical Press Agency/Getty Images). February 1957

British troops keep watch over Aden. (Photo by Bert Hardy/Getty Images). 1957

A British soldier talks with local dignitary in Aden which, until 1967, was part of a British protectorate. (Photo by Picture Post/Hulton Archive/Getty Images). 1957

An armed Protectorate Levy on guard on the Aden/Yemeni border (to protect fuel deposits against insurgents) during unrest in the British Protectorate of Aden. (Photo by Chris Ware/Keystone Features/Getty Images). 19th December 1958

RAF and Cameron Highlanders in Aden. (Photo by Bert Hardy/Picture Post/Getty Images). 1957

Oil tanks for refueling ships which call at the port of Aden in Yemen, now known as the Republic of Yemen. (Photo by Thal/Three Lions/Getty Images). Circa 1955

A Blue Tuareg, one of the Yemeni warriors who are carrying out attacks across their borders into Aden. (Photo by Keystone/Getty Images). Circa 1956

Jewish Yemeni immigrants on the street in Israel. (Photo by T. H. Bernsen/BIPs/Getty Images). 1st June 1956

A young Yemeni boy in the city of Taiz in the Yemen. (Photo by Bert Hardy/Picture Post/Getty Images). February 1957

A street stall in Yemen packed with a variety of consumer goods attended by a group of men wearing sarongs. (Photo by Three Lions/Getty Images). Circa 1950

The Nayib (Nawab) of Audalhi, brother of the Sultan of Aden. (Photo by Thomas Pakenham/Keystone/Getty Images). 25th July 1956

Royal Navy & RAF in the Radfau Mountains, Aden. A Royal Navy Wessex Helicopter taking off. On the airstrip is a RAF Twin Pioneer light transport. (Photo by Fox Photos/Getty Images). 5th June 1964

Field Marshal Sallal, president and prime minister of the new Yemen Republic, salutes at a victory parade. (Photo by Central Press/Getty Images). 2nd January 1963

A demonstrator is taken to the nearest police station by men of the Aden Police Force during civil war in Yemen. He was taking part in a demonstration organised by the Aden Trades Union Congress against Aden's joining the Federation of South Arabia. (Photo by Central Press/Getty Images). 26th September 1962

A Royal Airforce soldier cleaning sand from communication lines in the Yemen desert whilst mounted on a camel. (Photo by Central Press/Getty Images). 24th September 1962

Two Arabs stand guard over their Russian T34/85 tank in Yemen. (Photo by Central Press/Getty Images). 17th April 1964