Celso Caesar Moreno was an adventurer and a controversial political figure on the world stage, and Minister of Foreign Affairs of Hawaii under Kalākaua. Born in Italy, he fought in the Crimean War and lived throughout Asia, Hawaii and the United States, often taking sides with the indigenous underdog against British imperialism. He moved from one career to another, one grand scheme to another, often trying to convince governments to pay huge sums of money for his proposals. His efforts at establishing a trans-Pacific telegraph cable got official government authorization, but no financial backers. He became a naturalized American citizen in 1878, and a naturalized citizen of Hawaii in 1880. Moreno spent his final years living in Washington, D. C., trying to eliminate the padrone system that created slavery conditions within the Italian immigrant labor force.

The Minister of Foreign Affairs was a powerful office in the Kingdom of Hawaii, the Provisional Government of Hawaii and the Republic of Hawaii from 1843 to 1900. It made up one of the four offices of the monarchical or presidential cabinet which advised the Head of State of Hawaii on executive affairs. During the monarchy, ministers were also ex-officio members of the Privy Council and the House of Nobles in the legislature. During the republic, ministers were ex-officio members of both houses of the legislature. The head of state had the power to appoint the ministers but later Hawaiian constitutions limited the power the head of state had in removing the cabinet ministers by requiring a vote of no confidence from a majority of the elective members of the legislature. All acts of the head of state had to be countersigned by a minister.