So to answer this we got to know what happened in 1453. The biggest event that happened in 1453, particularly early April of 1453 if I recall correctly was the beginning of Sultan Mehmed II siege of Constantinople which fell barely a few months later. Mehmed II’s conquest of Constantinople was super interesting so there’s actually a great documentary kind of thing of Netflix called rise of empires: ottoman and it’s kind of cool to watch. This was an important event as it was seen to have ended the Middle Ages and helped jump start the renaissance and marks the end of the Eastern Roman Empire. With the Eastern Roman Empire falling it paved the way for a strong dominant Ottoman Empire to emerge leading to a religious shift from Christianity to Islam marking a significant blow to Christianity during the time.