In what main way did steam-powered warships and merchant ships affect empire building in the 1800s?

Steamships depended on fuel, especially coal, and needed regular supplies to keep traveling. This encouraged imperial powers to acquire or control ports and bases along important routes, helping them extend their empires. Greater naval and military power mattered too, but the distinctive effect of steam-powered ships was the need for far-flung refueling and resupply stations.

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