This article explores the global dimensions of the thought of George Perkins Marsh and his <cite>Man and Nature</cite> (1864). It argues that Marsh was not simply influenced by American versus European contrasts in environmental change, nor was his work based only on conservation ideas, being influenced also by the examples of acclimatisation movements within the British empire settlement colonies. He incorporated material on acclimatisation from Australia into his major work, and his acceptance, with reservations, of aspects of acclimatisation practice, for example global eucalyptus plant transfers, was a key factor making his work influential within those settlement colonies after publication of <cite>Man and Nature</cite>. This global context reinforces the sense of Marsh as a thinker of his times, embedded in a larger and older discourse over the fate of forests and other natural resources. Marsh's attempts to promote balance in humans' relations with nature led him to explore a renovationist and improvement oriented ethic as much as a restorationist or preservationist one. Though widely regarded as the father of conservation, his legacy is more ambiguous and more complex, and his influence reflects changing perceptions of European colonial impacts in the nineteenth century.