After 20 years of war in Afghanistan, Australian troops will be back home within months. 

They will not all return. Forty-one Australians died in the battle against a terror group that created mayhem on September 11, 2001. 

Ten Australians were among the nearly 3000 people killed when Al-Qaeda hijacked planes smashed into the World Trade Centre in New York. 

With Osama bin Laden captured and killed in 2011 and his organisation somewhat stymied, the allied task was broadly accomplished.