The part of Latvia between the west bank of the Daugava River and the Baltic Sea became the Duchy of Courland and Semigallia.

The Order of Livonia had already loaned the Grobiņa district (on the coast of Baltic Sea) to the Duke of Prussia.

He promised to transfer it to the Duchy of Courland after his death, but this plan failed and only later did Wilhelm Kettler regain this district.

As a result, Sweden gained control of what is today central and northern Latvia, which became Swedish Livonia.

In 1651 the Duchy established its first colony in Africa, St. Andrews Island at the Gambia River, and founded Jacob Fort there.

During this period, the Dutch took over both of Courland's colonies that lacked supplies and manpower, and the merchant fleet and factories suffered destruction.

Duke Jacob set about restoring the fleet and factories, but the Duchy of Courland never again reached its pre-war level of prosperity.

His successor, Friedrich Wilhelm Kettler, was only six years old and was under the regency of his uncle Ferdinand – a Polish general.

During this time the Great Northern War (1700–1721) began between Sweden and Russia with its allies – the Commonwealth, Saxony and Denmark.

In 1710, Friedrich Wilhelm married Anna Ioannovna (later Empress of Russia), but on his way back from St Petersburg, he took ill and died.

After the death of Friedrich Wilhelm, the next candidate for the seat of duke was Ferdinand Kettler, who, at the time, lived in Danzig.

One favorite was Maurice de Saxe, natural son of Augustus II the Strong, King of Poland.

Saxe had managed to gain support and was even mentioned as marrying Anna Ioannovna, Duchess of Courland at that time.

This was achieved in good measure due to service of Peter Lacy who was governor of Livonia from 1727 until his death in 1751.

Russian influence increased further when Frederick August III, the Elector of Saxony, in his successful bid to succeed his father on the Polish throne in the 1730s, agreed to grant Anna of Russia her choice of successor to the Courish duchy in exchange for Russian support in the War of the Polish Succession.

Von Biron received remarkable financial support from Russia and invested it in construction – for example, the Castle of Ruhenthal projected by the distinguished Italian architect Bartolomeo Rastrelli.

King Augustus III of Poland proclaimed his son, Carl Christian Joseph of Saxony, the next duke.

The situation became extremely tense – one part of the Landtag of Courland accepted von Biron, the other, Carl of Saxony.

The Empress Catherine II of Russia (reigned 1762–1796) solved this situation by recalling Ernst von Biron from exile in 1763.