Coalitions consist of bilateral alliances. This simple but often overlooked truth forms the central argument of this excellent analysis of Anglo-Italian relations from 1911 to 1919. Drawing on exhaustive research in Italian, British and French archives, combined with a thorough review of the secondary literature, Stefano Marcuzzi demonstrates that an alliance with the United Kingdom – to gain support for a war against Austria-Hungary rather than from commitment to the Entente – motivated Rome to sign the Treaty of London in 1915. As the book's subtitle indicates, he also shows how Italian political leaders balanced the desire for empire with the liberal commitment to completing the unification of Italy, while preserving public support for the war.

Marcuzzi divides his study into three parts. Part 1, ‘Making the Anglo-Italian Entente’, covers the period 1911–15 and discusses diplomatic and cultural relations between the two nations on the eve of the Great War. Part 2, ‘Integrating Italy into the Triple Entente’, examines Italy's participation in the alliance from the spring of 1915 to the summer of 1917. Part 3, ‘The Forked Road to Victory and Peace’, focuses on the period from the disaster at Caporetto in the autumn of 1917 to the peace conference that ended in the summer of 1919, and considers the ‘mutilated victory’. Marcuzzi sums up his findings in a succinct conclusion and adds an insightful epilogue, ‘Bloody Christmas in Fiume’, which presents the failed occupation of the city as the precursor of Mussolini's march on Rome. Excellent maps and photographs add clarity and depth to the book.

Italy's anomalous position in the European alliance system and its reluctance to go to war have long been known. Marcuzzi, however, demonstrates how the United Kingdom used a combination of carrots and sticks to push Rome off the fence and into the Entente camp. The British government funded propagandists within Italy, offered financial and territorial enticements, and exerted economic pressure by interdicting Italian shipping as part of its selective blockade of neutral nations. Those in the Italian government who favoured joining the Entente had two motives: completion of the Risorgimento by seizing from Austria-Hungary territory occupied by Italians, and expansion of the Italian empire through acquisition of territory in the Balkans, the Aegean, Africa and Asia Minor. They believed an alliance with Britain offered the best hope of achieving those goals. The April 1915 Treaty of London promised Rome South Tyrol, Istria, the Dalmatian coast, and the port of Trieste as well as colonies further away.

As Marcuzzi makes abundantly clear, Italy had a rocky relationship with the Entente throughout the war. It valued the alliance with Britain as a means to wage war against Austria-Hungary but distrusted France and Russia. Rome did not even declare war on the Ottoman Empire until August 1915 and on Germany until August 1916. Although it focused on maintaining good relations with London, misunderstandings and conflicts of interest characterised that relationship from the start. The British government treated Italy not as an equal partner but as a client. London grew frustrated that Rome would not send troops to Salonika to rescue Serbia and repeatedly criticised the Italians for failing to break through the Austrian defences on the Isonzo front or contain the Habsburg navy in the Adriatic. Neither British political leaders nor British generals had an appreciation of the difficulties the Italian army faced but repeatedly accused its soldiers of lacking fighting spirit. They based their criticism on prejudice and ethnic stereotypes. That criticism intensified following Caporetto and became an excuse for denying Italy what it had been promised in the Treaty of London.

Marcuzzi challenges the orthodox view that greed and poor negotiating at Versailles cost Italy its share of the spoils of war. The Italian ‘imperial project’ was doomed long before the delegates arrived in Paris. It was defeated by two powerful forces: Anglo-French imperial interests and Woodrow Wilson's commitment to self-determination of subject peoples, which Lloyd George used to subvert Italian interests in the Balkans. Britain and France favoured the new Yugoslav state over honouring promises made to Rome. The Kingdom of Serbs, Croats and Slovenes (later renamed Yugoslavia) got Dalmatia. The allies also thwarted Italy's colonial ambitions. Rome had to console itself with having finally completed Italian unification after acquiring the south Tyrol, Trieste, and most of Istria. Fiume, which Italian nationalists temporarily occupied, became a free city. Thus was born the myth of the mutilated victory.

Reviewers usually find something to criticise in any book, even if it means picking a nit. Stefano Marcuzzi provides them with little opportunity to do so. Some of his conclusions may be subject to debate, but he always supports them with solid evidence. It is not clear that Italy could have reinforced the expeditionary force in Salonika in time and with enough troops to save Serbia. Vittoria Veneto was an under-appreciated Italian victory, but it may not have hastened the end of the war as he suggests. His fascinating analysis of propaganda in general and ‘trench propaganda’ in particular merits further research.

Britain and Italy in the Era of the Great War sheds light on a neglected aspect of First World War studies and will remain an invaluable contribution to the literature for years to come.