Australian forces
US and Australian forces first fought alongside one another at the Battle of Hamel on the Western Front of World War I on 4 July 1918. The relationship, often referred to as mateship, forged over a hundred years ago has grown even closer over the years, with the two nations and New Zealand formalizing their security alliance by signing the Australia, New Zealand, United States Security Treaty (ANZUS Treaty) in San Francisco on 1 September 1951.