From the Middle Ages until the end of the Cold War, the Swedish military has had troops, ships and fortifications in the archipelago, to defend Stockholm. The only major enemy attack on Stockholm was committed by Russia, in 1719 to 1721. Today, most facilities are closed down. The local population relied on subsistence fishing and farming, isolated from Stockholm's tremendous progress in the 19th century, as tourists started to colonize the area. During the 20th century, many islands were de-populated, and transformed to summer resorts, with very small population during winter. Today, most island-dwellers commute to Stockholm for work, and enjoy maritime life as a hobby.