The soldiers’ mission was as dangerous as it was audacious: a trek of more than 500 miles through mountainous jungle in northern Burma to seize a Japanese-held airfield in World War II.

The threats were constant: fierce attacks by superior numbers of enemy troops, monsoon rains, tropical diseases and malnutrition.

When the airfield was finally taken three months later, only 130 able-bodied soldiers remained of the 2,600 who had crossed into Burma in 1944 with Merrill’s Marauders, a fabled unit that was one of the forerunners of the Army’s Special Operations elite, the 75th Ranger Regiment.

On Dec. 29, Russell Hamler, the last survivor of Merrill’s Marauders, died at a veterans’ hospital in Pittsburgh, his son Jeffrey said. He was 99.