The Great Famine of 1845–49 caused great bitterness among Irish people against the British government, which was perceived as having failed to avert the deaths of up to a million people. British support for the 1860 plebiscites on Italian unification prompted Alexander Martin Sullivan to launch a "National Petition" for a referendum on repeal of the union; in 1861 Daniel O'Donoghue submitted the 423,026 signatures to no effect.