1192: Birth of John III Vatatzes in Didymoteicho
after 1204: Vatatzes enters the service of the emperor of Nicaea. He becomes protovestiarios
1212: Marriage to emperor Theodore I Laskaris’ daughter, Irene
1222: He is named emperor. Birth of his heir, Theodore II. Rebellion of the Lascarids (brothers of Theodore Laskaris, pretenders to the throne)
1224-1225: Internal unrest. Conspiracy of the Nestongoi brothers and other nobles. Strict measures are taken to suppress rebellions
1224: Battle of Poimanenon. The Laskarid pretenders to the throne are arrested. A peace treaty is signed with the Latins of Constantinople. The territory of the Nicaean Empire expands. Lesbos, Chios, Samos and Ikaria are annexed
1225: Theodore Doukas enters Thessalonica and is crowned emperor
April 1230: Battle of Klokotnitsa. Theodore Doukas is defeated by the Bulgarian tsar Ivan II Asen
1232: Negotiations at Nicaea with delegates of the Pope for the union of the two Churches
1232-1233: Rhodes submits to the Empire of Nicaea
Winter of 1233: The assault of the Latin Emperor of Constantinople John de Brienne is repulsed
1234: Negotiations, initially at Nicaea (January) and subsequently at Nymphaeum (March) with the delegates of the Pope concerning the union of the Churches
Spring of 1235: Nicaea and the Bulgarians sign an alliance at Kallipolis. The son of John Vatatzes, Theodore II Laskaris, marries the daughter of Ivan Asen, Helen. The head of the Bulgarian Church is recognised as a Patriarch
1235: John Vatatzes and Ivan Asen campaign as allies against the Latins in an effort to capture Constantinople
1236: Second campaign of the two allies against the Latins. Ivan Asen defects
1237: A coalition of the forces of the Bulgarians, the Cumans and the Latins attacks the Empire of Nicaea. Ivan Asen gives up his military operations and requests a peace treaty with John Vatatzes
1241: Ivan Asen dies. A peace treaty is signed between the Latin emperor Baldwin de Courtenay and John Vatatzes. Empress Irene dies
1242: John Vatatzes campaigns against Thessalonica. John Doukas Angelos recognizes the suzerainty of Nicaea and relinquishes the title of emperor. The Mongols raid the Seljuk Sultanate of Rum
1243: The Sultan of Rum, Kaikosru II, and John Vatatzes, sign an agreement in Tripolis of the Maeander in order to face the Mongol horde
1244: Marriage with the daughter of the German emperor Frederick II Hohenstaufen, Constance. Death of the despotes John Doukas; he is succeeded by his brother Demetrios Doukas, following John Vatatzes’ consent
1246: Campaign against Demetrios Doukas Angelos. A large part of Macedonia, extending from the river Axios (Vardar) to the river Evros, is annexed to the Empire of Nicaea. John Vatatzes enters Thessalonica and Demetrios submits to his rule
1247-1248: Campaign in Thrace, capture of Tzouroulos and Vizye
1248: Rhodes falls to the Genoese. John Kantakouzenos is dispatched to recapture the island
1249: Negotiations between Epirus and Nicaea. The niece of John Vatatzes, Maria, is betrothed to Nicephoros, son of the despotes of Epirus, Michael II Doukas
1251: Michael II Doukas moves aggressively against the Nicaean possessions in Macedonia and attempts to seize Thessalonica
early 1252: John Vatatzes campaigns in western Macedonia. Michael Doukas capitulates and signs a cease-fire in Larissa
late 1253: John Vatatzes returns to Asia Minor
November 3rd 1254: Death of John III Vatatzes