The Pith Helmet / Safari Hat History:

Traditionally, the pith helmet was constructed of cork or pith typically from the Sola plant or similar.   It featured a cloth cover, designed to shade the wearer's head from the sun. It was made popular by Europeans and Americans in tropical climates.

Crude forms of pith helmets have existed since the middle of the 19th century, as early as the 1840s.  Somewhere around 1870 the pith helmet became popular with various European militaries in Europe's tropical colonies. At that time, the helmet was made of pith with small peaks at the front and back; it was covered by white cloth, and had small holes for ventilation. The chin strap could be in leather or brass chain, depending on occasions. The pith helmet soon became synonymous with the British Empire and its "Soldiers of the Queen". However, the pith helmet was used by all European colonial powers, and for quite a while even by the United States.

During the Anglo-Zulu War, British troops dyed their white pith helmets with tea for camouflage. Soon khaki-colored pith helmets became standard issues as well. European military personnel wore pith helmets operationally until the end of World War II, such as a version used by the Afrika Corps.

The pith helmet became so popular that it became a common civilian headgear for Westerners in the tropics from the end of the 19th Century. The civilian pith helmet was typically less decorative and more practical, not as tall as the military counterpart, and with a wide brim all round. Men, women and children wore it both in formal and casual occasions until the Second World War.
 
After the war, the Viet Minh of Vietnam copied the pith helmet from the former French colonizer, and adopted it as its own. Today it is still widely worn by both civilians and the military in Vietnam; it is similar to the pre-WWII civilian pith helmets, but covered in jungle green cloth, sometimes with a metal insignia at the front or back.

Outside Vietnam the pith helmet is now worn mainly by the British and Thai military. The pith helmet has also seen use as a form of identification by U.S. Marine Corps rifle range instructors at Parris Island and San Diego, similar to the Campaign hat worn by drill instructors.