The coming of the Soviet war scare in 1927 obliged all communist parties to spring to the defence of the world’s first socialist state. Kick-started by Britain’s severance of diplomatic relations in May, clear emphasis was placed from the very beginning on the role the Communist Party of Great Britain (CPGB) would play in combating a supposed British-led invasion of Soviet Russia. This article argues that the CPGB exhibited a distinctly sluggish approach to the war scare. Focus on the Russian war threat throughout 1927 was mitigated by the attention paid towards ongoing British intervention in China. Furthermore, though expected to welcome an ‘imperialist’ conflict as an opportunity to subvert the armed forces, thus creating a revolutionary situation, many British communists gained the Comintern’s ire in refusing to adopt such a strategy. The war scare, waging in ever greater force after 1927, came to be subsumed into the wider tenets of ‘class against class’. As such, this article argues that the tensions that engulfed the CPGB in the years between 1928 and 1929 over this new political doctrine included an anti-militarist dimension, with internal dissension over the war scare a key feature in the Comintern’s decision to remove much of the CPGB’s leadership by the end of 1929.