to operate around the world, coaling stations had to be provided for shipping routes and coal of the correct quality had to be transported there. Whilst the technology steadily improved, sail remained the most economical choice for ship-owners who wished to make a good return on the capital they had invested. Steam was an option only for a limited number of trades until the 1860s, focussing on routes requiring scheduled services and/or reliable average speeds on a voyage – and only where the customer was prepared to pay the higher costs involved. Most of this was passenger transport and mail contracts. Only when the much more fuel efficient triple expansion engine had become common (by the 1890s) were all shipping routes fully commercially viable for steamers. Ironclads are steam-propelled warships of the later 19th century, protected by iron or steel armor plates. The ironclad was developed as a result of the vulnerability of wooden warships to explosive or incendiary shells. The first ironclad battleship, , was launched by the French Navy in 1859; she prompted the British Royal Navy to start building ironclads. After the first clashes of ironclads took place during the American Civil War, it became clear that the ironclad had replaced the unarmored line-of-battle ship as the most powerful warship afloat. In 1880, the American passenger steamer Columbia became the first ship to utilize the dynamo and incandescent light bulb. Furthermore, Columbia was the first structure besides Thomas Edison's laboratory in Menlo Park, New Jersey to use the incandescent light bulb. Greek War of Independence The Greek War of Independence was a successful war waged by the Greeks to win independence for Greece from the Ottoman Empire. Success at sea was vital for the Greeks. If they failed to counter the Ottoman Navy, it would be able to resupply the isolated Ottoman garrisons and land reinforcements from the Ottoman Empire's Asian provinces at will, crushing the rebellion. The Greeks decided to use fireships and found an effective weapon against the Ottoman vessels. Conventional naval actions were also fought, at which naval commanders like Andreas Miaoulis, Nikolis Apostolis, Iakovos Tombazis and Antonios Kriezis distinguished themselves. The early successes of the Greek fleet in direct confrontations with the Ottomans at Patras and Spetsai gave the crews confidence, and contributed greatly to the survival and success of the uprising in the Peloponnese. Despite victories at Samos and Gerontas, the Revolution