Duncan Hallas (1925-2002) was one of the 33 founding members of the Socialist Review Group, the forerunner of the International Socialists and the Socialist Workers Party. A genuine working-class autodidact, his contribution to the international socialist tradition spanned the fields of theory, propaganda and action. For Duncan, Marxism was living, breathing revolutionary practice. His life was shaped by his experience as a young factory worker growing up in Manchester. Always the revolutionary fighter, he took part in an apprentices' strike in Manchester in 1941, an army mutiny in Egypt just after the Second World War and later became the driving force behind establishing rank and file teachers' organisation in the late 1960s. As part of the full-time leadership of the Socialist Workers Party for almost 25 years, Duncan maintained a stream of articles explaining everything from basic Marxist ideas to combating various forms of reformism and, above all, conveying the depth of the revolutionary tradition. His grasp of the united front helped shape the Anti-Nazi League in the 1970s. He was one of the organisation's most popular speakers, spellbinding and erudite, he would hold his audience, whether a handful of comrades or thousands in a packed hall anywhere in the world, in the palm of his hand. His commitment to the victory of the working-class cause internationally was as strong when he died in 2002 as it was when he started working for socialism at the beginning of the 1940s. This book is a tribute to a remarkable life and a call to a new generation to enrich and deepen their understanding of revolutionary socialism through Duncan's work. That work left us many bullets to continue with the fight. Let's use his ammunition wisely.