Campbell's family announced that the singer had died on Tuesday morning in Nashville, Tennessee. The country music star had been suffering from Alzheimer's disease for several years.

"It is with the heaviest of hearts that we announce the passing of our beloved husband, father, grandfather, and legendary singer and guitarist, Glen Travis Campbell, at the age of 81, following his long and courageous battle with Alzheimer's disease," his family said in a statement.

The singer, famous in the 1960s and 70s for hits like "Rhinestone Cowboy," "Wichita Lineman" and "Gentle on My Mind," embarked on a nationwide farewell tour that ended in November 2012 soon after being diagnosed with the illness.

He went on to release a documentary about his struggle with the disease called "Glen Campbell... I'll Be Me" in 2014 as well as a final studio album this past June, entitled "Adios," recorded after the tour had finished.

'A country boy who sings'

Born in Arkansas as one of 12 children, Campbell moved to Albuquerque, New Mexico, to join his uncle's band and appear on his uncle's radio show. By his early 20s, he had formed his own group, the Western Wranglers, and moved to Los Angeles.

In California, Campbell focused on his career as a guitarist before becoming a fixture on the US music charts, radio and television in the 1960s and 1970s.

He won six Grammy Awards in a career of more than 50 years, releasing more than 70 of his own albums.

Campbell's tumultuous and eventful career drove him into drug and alcohol abuse. In 2003, he was arrested near his home in Phoenix, Arizona, for causing a minor traffic accident.

Campbell was married four times and had eight children. He is survived by his wife, their three children, and five his children from previous marriages.

"I'm not a country singer per se," Campbell once said. "I'm a country boy who sings."

ss/cmk (AP, Reuters)