This is true, not having a navy has shown itself to be a weakness of many nations/civilizations in the past. And there are also good reasons why this is so. Not having a navy strongly impacts a civilizations ability to maneuver around certain points and go around them. It also limits the ability to trade with other natons. Not to mention the additional value of having the firepower of ships (those that had cannons later on at least).
The purchase of Alaska in 1867 marked the end of Russian efforts to expand trade and settlements to the Pacific coast of North America, and became an important step in the United States rise as a great power in the Asia-Pacific region.
