Through four regimes between 1815 and 1870, the French would regularly invent new rationales and purposes for empire. A domestic crisis of legitimization led to the invasion of Algeria in 1830. So began a French settler colony in which barely half the settlers even came from France. The revolutionaries of 1848 annexed the colonies, making them national territory. While chattel slavery was legally abolished throughout the empire, annexation meant different things in different places. Colonial incoherence continued. Missionaries fostered and legitimized imperial expansion, though the imperial state never found them completely reliable. Military entrepreneurs in Senegal and Indochina had their own agendas, and did Emperor Napoleon III, who envisaged an “Arab Kingdom” in Algeria. He also sought to expand the empire indirectly, through a disastrous scheme to place a Habsburg on a Mexican throne. The prison colony provided another brutal avenue of colonial expansion. French imperial capitalism generally prospered, though the French were so outmaneuvered by the British after building the Suez Canal that they overshadowed the French role altogether. By 1870, the whole of the French empire still somehow seemed less than the sum of its parts.