Between 2000 and 2003 he wrote his first history, Kokoda – the story of the first land defeat of the Japanese in the Second World War; followed by Vietnam: The Australian War – a history of Australia's 15-year military involvement in Vietnam. Vietnam won the NSW Premier's Prize for Australian history, and was shortlisted for the Prime Minister's Prize for Non-Fiction; both Vietnam and Kokoda were shortlisted for the Walkley Award for Non-Fiction.

His next book, Hiroshima Nagasaki: The Real Story of the Atomic Bombings and Their Aftermath, a controversial history of the atomic bomb, was shortlisted for the NSW Premier's Prize for History and published in the United States, Britain and Australia to critical acclaim.

In 2010 Ham co-wrote and presented the documentary, All the Way, produced by November Films in conjunction with the Australian Broadcasting Corporation (ABC), based on his history of the Vietnam War. In 2008 he was involved in the production of a documentary based on Kokoda, produced by Pericles Films, the ABC and Screen Australia. In 2012 Ham set up an electronic publishing business called Hampress, which publishes short ebooks and classic audiobooks.

In 2013 Ham published 1914: The Year the World Ended, in Britain and Australia, which won the Queensland Literary Award for Non-Fiction in 2014. His book Sandakan: The Untold Story of the Sandakan Death Marches, released the previous year, was shortlisted for the Prime Minister's Literary Awards.

In 2016-17 he published his most recent books, Passchendaele: Requiem for Doomed Youth and Young Hitler in Australia and Britain. He is a regular contributor to Amazon's Kindle Single platform, having published 1913, The Target Committee and, with the psychotherapist Bernie Brown, Honey, We Forgot the Kids, an examination of the state of families and childcare in the West.

Christmas 1913: In Britain, people are debating a new dance called ‘the tango’.

In Germany, they are fascinated by the wedding of the Kaiser’s daughter to the Duke of Brunswick. Little did they know that their world was on ‘The Eve of War’, a catastrophe that was to engulf the continent, cost millions of lives, and change the course of the century.

And yet behind the scenes, the Great Powers were marching towards what they thought was an inevitable conflict.

In this controversial and concise essay, the military historian Paul Ham argues that the First World War was not an historical mistake, a conflict into which the Great Powers stumbled by accident. Nor was it a justified war, in which uncontained German aggression had to be defeated.

Instead the politicians and generals of the day willed the war, and prepared for it - but eventually found themselves caught up in an inferno they could no longer control.