Estonian War

The Estonian War was a conflict between Sweden and the Livonian Order (along with their ally, Riga) over the status of Estonia.

Background
Following the Novgorod War, Sweden wished to expand their influence over the Baltic, but were reluctant to be more aggressive due to high aggressive expansion. The province of Narva was officially claimed on 19 August 1451.After the Novgorodian Rebellions, King Gustav I Drake decided it was best to take the lands now, before Poland or Muscovy gets them.

Narva and Reval
Sweden declared war on the Livonian Order on 20 May 1454, and immediately send troops to occupy Narva, which was done on 3 July. The fort at Reval was sieged down after that, but when Rigan forces attempted to enter Ingermanland, they were engaged back in Narva on 6 September and were completely destroyed. Livonian forces in Ingermanland returned to also attack Swedish troops and were also destroyed.

The "true" siege of Reval began on 6 October. It was during this siege that Gustav I died, and his wife Christina Drake took over as Queen-Consort. The castle finally fell on 8 September 1455. The army was ordered to return to Nyland, as Rigan troops were bypassing the fort at Viborg using ships. This landing force, as well as another one at Viborg, were defeated easily by the Swedes. Livonian troops used this to their advantage by attempting to retake Reval, but Swedish troops arrived in time - led by the newly recruited Oskar Liljencrantz - and attacked a slow-moving portion of the army and destroyed it.

Liefland and Lettgallen
From this point onwards, much of the war was a back and forth between multiple provinces. Swedish troops besieged Fellin (located in Liefland), the capital of the Livonian Order, on 13 March 1456. They were forced to return to Nyland though due to more incoming Rigan troops. They returned to Fellin on 13 July, and again left to engage Rigan troops in Dorpat. While the Rigans were reinforced with many Livonian troops, they were ultimately defeated on 25 September, and Dorpat was occupied thereafter.

To keep control of Dorpat, instead of besieging Fellin, the focus moved to Dunaburg, capital of Lettgallen. Reval was under threat of being retaken, so Swedish troops moved back yet again, and were attacked early in Fellin. Sweden narrowly won, losing more men than the Livonians and Rigans, and peace was considered.

End
The Treaty of Abo was signed on 2 April 1457, which ceded Osel, Reval, Liefland, Dorpat, and Narva to Sweden. A day later, these were granted to the new nation of Estonia, as a vassal under Sweden.