Havelock

Havelock is defined by the American Heritage Dictionary as "a cloth covering for a cap, having a flap to cover and protect the back of the neck."  The Oxford English Dictionary specifies the color of the fabric for havelocks as white.  This covering is named after Major-General Sir Henry Havelock.  Sir Havelock was stationed in India where the sun was a problem for the British forces.  It is not evident if Sir Havelock had a hand in creating havelocks, but I assume it was named after him simply because of his work in the Indian Rebellion of 1857.

The Oxford English Dictionary shows the first use of the work havelock in literature was by Harriet Beecher Stowe in 1861, "He is a fine-looking man with black eyes and hair, set off by a white havelock."  The last use of the term listed in the OED is from Harper's Magazine in 1880 as a reference to fashion, "A poncho and havelock cap comprise the rubber clothing outfit."  

Sources:  American Heritage College Dictionary 4th Edition, Oxford English Dictionary