What happened on April 15 ?

In the United States, April 15 is the official deadline for filing tax returns: all forms mailed to the IRS must be postmarked no later than this day, so many post offices across the country stay open until midnight to accommodate procrastinators (or those who owe tax and want to wait as late as possible to pay). (If this day falls on the weekend, as in 2006, the following Monday becomes the deadline. Additionally in 2006, Patriot's Day moved the tax deadline to Tuesday, April 18, for those in the seven states and the District of Columbia which celebrate Patriot's Day.)

Ancient Latvia ? Tipsa Diena was observed.

Arirang Festival is held in North Korea to commemorate Kim Il-sung's birth.

Father Damien Day ? celebrated annually in Hawai'i.

Roman Empire ? the Fordicia was celebrated in honor of Terra.

Major League Baseball celebrates "Jackie Robinson Day" each April 15 in all MLB ballparks.

Saint Petrus Gonzalez

Saint Paternus

Blessed Waltman of Antwerp

Saint Basilissa

Saint Hunna.