Noon bell

Sándor Wágner: The heroism of Titusz Dugovics, romantic painting, 19th century.

Battle of Belgrad, Hungarian painting from the 19. century. In the middle Giovanni da Capistrano (Kapisztrán János) with the cross in his hand.

During the Siege of Belgrade (the Hungarian name: Nándorfehérvár. The city was part of Hungary until 1521). In 1456, Hungarian noblemen John Hunyadi (leader of the Hungarian royal army) and Mihály Szilágyi (Captain of the castle of Nándorfehérvár/ Belgrade) defended the city against the onslaught of the Ottoman Sultan Mehmed II. The siege finished with a Christian victory. During the siege, Pope Callixtus III ordered the bells of every church to be rung every day at noon, as a call for believers to pray for the defenders of the city. However, in many countries (like England and Spanish Kingdoms), news of the victory arrived before the order, and the ringing of the church bells at noon thus transformed into a commemoration of the victory. The Pope didn't withdraw the order, and Catholic and the older protestant churches still ring the noon bell to this day.^[1][2][3][4]

1. ^ István Lázár: Hungary: A Brief History (see in Chapter 6)
2. ^ Kerny, Terézia (2008). "The Renaissance - Four Times Over. Exhibitions Commemorating Matthias’s Accession to the Throne". The Hungarian Quarterly. Budapest, Hungary: Society of the Hungarian Quarterly. pp. 79–90. http://www.ceeol.com/aspx/issuedetails.aspx?issueid=36917033-77c7-4622-8f76-dae90f531363&articleId=ca7d4a8b-cee0-4d8b-beab-fb1536ba3597. "On July 22, 1456, John Hunyadi won a decisive victory at Belgrade over the armies of Sultan Mehmed II. Hunyadi’s feat—carried out with a small standing army combined with peasants rallied to fight the infidel by the Franciscan friar St John of Capistrano— had the effect of putting an end to Ottoman attempts on Hungary and Western Europe for the next seventy years, and is considered to have been one of the most momentous victories in Hungarian military history. The bells ringing at noon throughout Christendom are, to this day, a daily commemoration of John Hunyadi’s victory." 
3. ^ http://www.hungarianhistory.com/lib/hunyadi/hu01.htm
4. ^ http://nq.oxfordjournals.org/cgi/reprint/CLXVII/sep08/171-d