Final answer:
Mazzini's dream of a republic failed due to opposition from other nationalist leaders, lack of popular support, and intervention of foreign powers.
Step-by-step explanation:
Mazzini's dream of a republic failed due to several factors. First, he faced opposition from other nationalist leaders who had different visions for Italy's future. Second, he lacked popular support and was unable to rally enough people to his cause. Finally, his dream was thwarted by the intervention of foreign powers, such as Austria and France, who were hostile to the idea of Italian unification.
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