Jimmy Webb pays tribute to 'extraordinary genius' Glen Campbell

— -- Glen Campbell passed away Tuesday at age 81 after a long battle with Alzheimer's disease and his longtime friend, Jimmy Webb, hopes others will appreciate the legacy he left behind.

Webb, who wrote many of Campbell's signature hits and worked with him throughout his life, told ABC News back in May about his relationship and fruitful collaboration with the multi-talented musician.

Prior to launching his career as a solo artist, Campbell was a sought-after session guitarist, playing on countless hits by a variety of music stars, as Webb noted.

"He could sit and play with any guitar player in the world, from George Benson to Eric Clapton. Paul McCartney knew he was a great guitar player," Webb maintained. "I think all this will come to the surface as the years pass and people realize what an extraordinary genius Glen really was."

Reflecting on Campbell's session work, Webb believes his legacy is strong.

"I think he's one of the great largely unknown influences on American pop music in the '60s, because he played on so many significant records," Webb said about Campbell. "He was just, in his own way, I believe, as influential on American music as perhaps The Beatles were on British music."

Webb admitted that when he and Campbell first met, their opposing political beliefs caused some friction; he was a liberal and Campbell was a conservative. But they were able to put aside their differences.

"We established a place in the middle of our lives where we could work," Webb explained, "and we could give reign to creativity and emotion and reveal deep parts of ourselves as we worked on music."

Webb said he had great respect for Campbell for deciding to tour late in his life, despite struggling with the effects of Alzheimer's disease. Campbell first revealed his diagnosis in 2011, released his album "Ghost on the Canvas" and embarked on a lengthy "goodbye" tour through most of 2012.

"He finished like a champion," Webb said. "And maybe he was the bravest man I've ever known."