Battle of Mentana The Battle of Mentana was fought on November 3 , 1867 near the village of Mentana between French - Papal troops and the Italian volunteers led by Giuseppe Garibaldi , who were attempting to capture Rome , then the main centre of the peninsula still outside of the newly unified Kingdom of Italy . The battle ended in a victory by the French - Papal troops . Background . When the first Italian Parliament met in Turin , Victor Emmanuel II of Savoy was proclaimed King of Italy on March 17 , 1861 , and Rome was declared capital of Italy on March 27 , 1861 . However , the Italian government could not take its seat in Rome because Emperor Napoleon III maintained a French garrison there to prop up Pope Pius IX . This created an unstable political situation that led to much strife , both internal and external . In 1862 Giuseppe Garibaldi , the hero of the unification , organized an expedition from Sicily , under the slogan " Roma o Morte " ( Rome or Death ) that attempted to take Rome . However , after crossing the Straits of Messina , the expedition was stopped at Aspromonte ( known as the Aspromonte incident of 1862 ) by Italian troops . Garibaldi was wounded , taken prisoner , but subsequently released . This act was forced on the Italian government by Napoleon III , who threatened military intervention if Garibaldi were not stopped . On September 15 , 1864 , the September Convention was signed by the Italian government and Napoleon III . The Italian government agreed to protect the Papal States against external menaces and agreed to move the capital of Italy from Turin to Florence . The French garrison would be withdrawn from Rome within two years , during which time the Papal army would reorganize itself into a credible force . This unpopular agreement led to numerous riots ( primarily in Turin which objected to its loss of status ) and to renewed demands for the Italian government to take possession of its capital , Rome . Garibaldi ' s expedition . On August 12 , 1866 , in the aftermath of the Third Italian War of Independence , Italy gained Mantua and Venice . Now only Rome and its neighbourhood were missing to complete the territorial unity of the state . In December of the same year , the last French battalions embarked from Civitavecchia to France . On September 9 , 1867 , at a congress in Geneva , Garibaldi declared that the Papacy was " the negation of God . . . shame and plague of Italy " . At the time , his popularity was at its apex , since he was the only Italian general who had obtained significant successes during the last war against Austria . He was therefore left free to organize a small army of about 10 , 000 volunteers . The plan was to march against Rome , while a riot was to break out inside the city . However , Garibaldi ' s overt moves allowed the French emperor Napoleon III to send a relief force in time to Rome . Apart from this official support , the Papal army was at the time composed mostly of French and European volunteers . Invasion of Lazio . Garibaldi ' s volunteers invaded Lazio , the region that contains Rome , in October 1867 . A small contingent , led by Enrico Cairoli with his brother Giovanni and 70 companions , made a daring attempt to take Rome . The group embarked in Terni and floated down the Tiber . Their arrival in Rome was to coincide with an uprising inside the city . On 22 October 1867 , the revolutionaries inside Rome seized control of the Capitoline Hill and of Piazza Colonna . However , when the Cairoli and their companions arrived at Villa Glori , on the northern outskirts of Rome , the uprising had already been suppressed . During the night of 22 October 1867 , the group was surrounded by Papal Zouaves , and Giovanni was severely wounded . Enrico was mortally wounded and bled to death in Giovanni ' s arms . At the summit of Villa Glori , near the spot where Enrico died , there is a plain white column dedicated to the Cairoli brothers and their 70 companions . About 100 meters to the left from the top of the Spanish Steps , there is a bronze monument of Giovanni holding the dying Enrico in his arm . A plaque lists the names of their companions . Giovanni never recovered from his wounds and from the tragic events of 1867 . According to an eyewitness , when Giovanni died on 11 September 1869 : The last group of rebels inside Rome , in the quarter of Trastevere , was bloodily captured on October 25 . The captured Roman rebels were executed in 1868 . Garibaldi with about 8 , 100 men , had reached the neighbourhood of Rome , occupying Tivoli , Acquapendente and Monterotondo . Here he halted his march , waiting for an insurrection which never occurred . Minor fights ensued , but without relevant results . Three days later he advanced on the Via Nomentana , in order to spur the rebels to action , but returned to Monterotondo the following day . On the same day , Italian troops had crossed the boundary to halt the Garibaldine army , and a French force had disembarked in Civitavecchia . Battle . In the first hours of November 3 , the Papal troops , under general Hermann Kanzler , and the French expeditionary corps , under general Balthazar de Polhès , moved from Rome to attack Garibaldi ' s army along the Via Nomentana . The Allies were well trained and organized , and the French troops were armed with the new Chassepot rifle ; Garibaldi ' s volunteers were less well organized , and nearly without any artillery or cavalry , apart a small squadron led by Garibaldi ' s son , Ricciotti . The Papal vanguards met Garibaldi ' s volunteers about 1 . 5 km south of the village Mentana , midway from Rome to Monterotondo . The three battalions defending the position were quickly dislodged . However , Garibaldi ' s resistance stiffened in the fortified village , and repeated Papal attacks were all pushed back until nightfall . The situation changed when three companies of Zouaves occupied the road from Mentana and Monterotondo . Garibaldi intervened in person , but could not prevent his troops being routed . The survivors entrenched in the castle of Mentana ; some surrendered the following morning , and others fled to Monterotondo . On November 4 Garibaldi retreated to the Kingdom of Italy with 5 , 100 men . In Mentana , the monument " Ara dei Caduti " ( Altar of the Fallen ) is built over the mass grave of the Italian patriots who died in the battle . Subsequently , a French garrison remained in Civitavecchia until August 1870 , when it was recalled following the outbreak of the Franco - Prussian War . Rome was captured by the Italian Army on September 20 , 1870 , finally giving Italy possession of its capital .