Saaremaa in the context of "Reformation in Denmark–Norway and Holstein"

Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Russia. The territory of Estonia consists of the mainland, the larger islands of Saaremaa and Hiiumaa, and over 2,300 other islands and islets on the east coast of the Baltic Sea. Its capital Tallinn and Tartu are the two largest urban areas. The Estonian language, of the Finnic family, is the official language and the first language of the majority of its population of nearly 1.4 million. Estonia is one of the least populous members of the European Union and NATO.

Present-day Estonia has been inhabited since at least 9,000 BC. The medieval indigenous population of Estonia was one of the last pagan civilisations in Europe to adopt Christianity following the Northern Crusades in the 13th century. After centuries of successive rule by the Teutonic Order, Denmark, Sweden, and the Russian Empire, a distinct Estonian national identity began to emerge in the mid-19th century. This culminated in the 1918 Estonian Declaration of Independence from the then-warring Russian and German empires. Democratic throughout most of the interwar period, Estonia declared neutrality at the outbreak of World War II, but the country was repeatedly invaded and occupied, and ultimately annexed into the USSR. Throughout the de facto Soviet occupation, from World War II until 1991, Estonia's de jure state continuity was preserved by diplomatic representatives and the government-in-exile. Following the 1988–90 "Singing Revolution" against Soviet rule, full independence was restored on 20 August 1991.

The Duchy of Estonia (Estonian: Eestimaa hertsogkond, Danish: Hertugdømmet Estland Latin: Ducatus Estoniae), also known as Danish Estonia, was a direct dominion (Latin: dominium directum) of the King of Denmark from 1219 until 1346 when it was sold to the Teutonic Order and became part of the Ordensstaat.

Denmark rose as a great military and mercantile power in the 12th century. It had an interest in ending the frequent Estonian attacks that threatened its Baltic trade. Danish fleets attacked Estonia in 1170, 1194, and 1197. In 1206, King Valdemar II and archbishop Andreas Sunonis led a raid on Ösel island (Saaremaa). The Kings of Denmark claimed Estonia, and this was recognised by Pope Honorius III. In 1219, the fleet of Valdemar II landed in the harbor of Lindanise (Tallinn) and defeated the local Estonians in the Battle of Lindanise. This brought northern Estonia under Danish rule until the Estonian uprising in 1343, after which the territories were taken over by the Teutonic Order. They were sold by Denmark in 1346.

Estonia under Swedish rule signifies the period of time between 1561 and 1710, when present-day Estonia was under the rule of the Swedish Empire. In the wake of the breakup of the State of the Teutonic Order, the Baltic German local nobility in the areas of Harrien (Harjumaa) and Wierland (Virumaa), as well as the city of Reval (Tallinn) in June 1561 (and somewhat later Jerwen (Järvamaa)) asked for and were granted protection by the Swedish king Eric XIV, leading to Swedish involvement in the Livonian War. At the conclusion of hostilities in 1583, Sweden was in control of the northern parts of modern Estonia and Dagö (Hiiumaa island); the Duchy of Estonia was created from this territory. Following renewed wars between Poland and Sweden, the southern parts of present-day Estonia (then Livonia) were incorporated into Sweden by the Treaty of Altmark in 1629. Sweden also conquered the island of Ösel (Saaremaa) from Denmark, and were thus in control of all of present-day Estonia.

The time of Swedish rule came to an effective end in 1710, when all the Swedish Baltic provinces capitulated to Russian troops during the end-stages of the Great Northern War. Russian hegemony was formalized in 1721.

Swedish Livonia (Swedish: Svenska Livland) was a dominion of the Swedish Empire from 1629 until 1721. The territory, which constituted the southern part of modern Estonia (including the island of Ösel ceded by Denmark after the Treaty of Brömsebro) and the northern part of modern Latvia (the Vidzeme region), represented the conquest of the major part of the Polish-Lithuanian Duchy of Livonia during the 1600–1629 Polish-Swedish War. Parts of Livonia and the city of Riga were under Swedish control as early as 1621 and the situation was formalized in the Truce of Altmark 1629, but the whole territory was not ceded formally until the Treaty of Oliva in 1660. The minority part of the Wenden Voivodeship retained by the Polish–Lithuanian Commonwealth was renamed the Inflanty Voivodeship ("Livonian Principality"), which today corresponds to the Latgale region of Latvia.

Riga was the second largest city in the Swedish Empire at the time. Together with other Baltic Sea dominions, Livonia served to secure the Swedish dominium maris baltici. In contrast to Swedish Estonia, which had submitted to Swedish rule voluntarily in 1561 and where traditional local laws remained largely untouched, the uniformity policy was applied in Swedish Livonia under Karl XI of Sweden: serfdom was abolished, peasants were offered education as well as military, administrative or ecclesiastical careers, and nobles had to transfer domains to the king in the Great Reduction.

The Gulf of Riga, also known as the Bay of Riga or the Gulf of Livonia, is a bay of the Baltic Sea between Latvia and Estonia.

The island of Saaremaa (Estonia) partially separates it from the rest of the Baltic Sea. The main connection between the gulf and the Baltic Sea is the Irbe Strait.

Faddey Faddeyevich Bellingshausen or Fabian Gottlieb Benjamin von Bellingshausen (20 September [O.S. 9 September] 1778 – 25 January [O.S. 13 January] 1852) was a Russian cartographer, explorer, and naval officer of Baltic German descent, who attained the rank of admiral. He participated in the first Russian circumnavigation of the globe, and subsequently became a leader of another circumnavigation expedition that discovered the continent of Antarctica. Like Otto von Kotzebue and Adam Johann von Krusenstern, Bellingshausen belonged to a cohort of prominent Baltic German navigators which helped Russia launch its naval expeditions.

Bellingshausen was born on the island of Saaremaa (Ösel), to the Bellingshausen family [de]. He started his service in the Russian Baltic Fleet, and after distinguishing himself joined the first Russian circumnavigation of the Earth in 1803–1806, serving on the merchant ship Nadezhda under the captaincy of Adam Johann von Krusenstern. After the journey, he published a collection of maps of the newly explored areas and islands of the Pacific Ocean. Subsequently, he commanded several ships of the Baltic and Black Sea Fleets.

The Courland Peninsula (Latvian: Kurzemes pussala, German: Kurland), also sometimes known as the Couronian Peninsula, is a distinct geographical, historical and cultural region in western Latvia. It represents the north-westernmost part of the broader region of Courland (Latvian: Kurzeme). The peninsula is renowned for its unique coastline, significant natural areas, rich history, and as the primary homeland of the indigenous Livonian people. Fourteen coastal villages located along the peninsula's northern and western shores constitute the officially recognized Livonian Coast (Livonian: Līvõd Rānda), the core area of Livonian settlement and culture.

Geographically, the peninsula is clearly defined by major bodies of water. It is bordered by the open Baltic Sea to the west and northwest, the Irbe Strait (Latvian: Irbes jūras šaurums) to the north (separating it from the Estonian island of Saaremaa), and the large, shallow Gulf of Riga to the east. It covers a significant portion of northwestern Latvia, encompassing parts of the modern administrative regions of Ventspils Municipality, Talsi Municipality, and potentially small parts of Kuldīga Municipality.