Task: Question Understanding
Input (English): Passage: Venice had held several islands in the Aegean and the Ionian seas, together with strategically positioned forts along the coast of the Greek mainland since the carving up of the Byzantine Empire after the Fourth Crusade. However, with the rise of the Ottomans, during the 16th and early 17th centuries, they lost most of these, such as Cyprus and Euboea  to the Turks. Between 1645 and 1669, the Venetians and the Ottomans fought a long and costly war over the last major Venetian possession in the Aegean, Crete. During this war, the Venetian commander, Francesco Morosini, came into contact with the rebellious Maniots, for a joint campaign in the Morea. In 1659, Morosini landed in the Morea, and together with the Maniots, he took Kalamata. However, he was soon after forced to return to Crete, and the Peloponnesian venture failed. In 1683, a new war broke out between Austria and the Ottomans, with a large Ottoman army advancing towards Vienna. In response to this, a Holy League was formed. After the Ottoman army was defeated in the Battle of Vienna, the Venetians decided to use the opportunity of the weakening of Ottoman power and its distraction in the Danubian front so as to reconquer its lost territories in the Aegean and Dalmatia. On 25 April 1684, the Most Serene Republic declared war on the Ottomans. Aware that she would have to rely on her own strength for success, Venice prepared for the war by securing financial and military aid in men and ships from the Knights of Malta, the Duchy of Savoy, the Papal States, and the Knights of St. Stephen. In addition, the Venetians enrolled large numbers of mercenaries from Italy and the German states, especially Saxony and Brunswick.
Question: In which year the most Serene Republic declared war?
Output (English): date