International Amateur Radio Union

World Amateur Radio Day

Days of Military Honour

Victory over the Teutonic Knights in the Battle of the Ice (Russia; Julian Calendar)

Japanese patent law

Invention Day (Japan)

International Day For Monuments and Sites

International Day For Monuments and Sites

Public holidays in Zimbabwe

Independence Day (Zimbabwe)

Friendship Day

Friend's Day (Brazil)

Public holidays in Poland

Coma Patients' Day (Poland)

Armed Forces Day

Army Day (Iran)

April 18 (Eastern Orthodox liturgics)

Christian feast day:
April 18 (Eastern Orthodox liturgics)

Beatification

Christian feast day:
Blessed Savina Petrilli

Perfectus

Christian feast day:
Perfectus

Molaise of Leighlin

Christian feast day:
Molaise of Leighlin

Beatification

Christian feast day:
Blessed Marie of the Incarnation

Saint Galdino

Christian feast day:
Galdino della Sala

Eleutherius and Antia

Christian feast day:
Eleutherius and Antia