As legendary rock band Cold Chisel prepare for their 50th-anniversary tour, Australian Story looks back over the band's colourful history and examines why they have become such an essential part of our cultural history."The songs start as hits and then they become anthems," says journalist, writer and fan Trent Dalton. "And then, with time, they become sacred."Music writer Mark Mordue – a Chisel fan since he was a teenager in Newcastle – says the songs are embedded into the national psyche. "Songs like Flames Trees and Khe Sanh, they're stone-cold classics and they're as much a part of who we are as Henry Lawson's story The Driver's Wife or Banjo Paterson's The Man from Snowy River."In a special 45-minute episode, all four surviving members – Jimmy Barnes, Ian Moss, Don Walker and Phil Small – recount how the band rose from industry outsiders filling rough suburban pubs to arena-filling rock royalty.An extraordinary live band, they were a combustible unit and broke up for the first of many times in 1983. "When we split up, I thought within two years it would be ‘Cold who?'," says guitarist Moss. "But it's the songs. It all comes down to the songs."This episode looks beyond the band's history to explore the enduring impact and appeal of those songs."People come up to me in the street and say, I played your songs at my son's 21st. I danced my first dance with my wife to your songs. I buried my son or buried my father to your songs," Jimmy Barnes tells Australian Story.Vietnam veteran Bob King describes Khe Sanh as the "unofficial national anthem" of Australia, since most people know the lyrics better than they do for the official anthem.As the band prepare for the upcoming tour, songwriter and keyboard player Don Walker says he is looking forward to performing again."There's good mutual history, there's bad mutual history. The bad mutual history tends to fade and get lost in the sepia. Until next time we try and do something…"