National Pet Memorial Day in US

Commemoration of the mass hanging of the Saint Patrick's Battalion on September 12 (Mexico);

Día de los Niños Héroes in Mexico on September 13 (in memory of 6 young Mexican cadets who died in the battle of September 13, 1847 during the Mexican-American War);

Beginning of the Week of Remembrance of the Farropiglia Revolution in Brazil on September 13;

The Fast of Gedalia in Israel on September 13 (Heb.: צוֹם גְּדַלְיָה - is a minor Jewish fast day from dawn until dusk to lament the assassination of the righteous governor of Judah. His murder ended Jewish autonomy following the destruction of the First Temple);

Battle of Britain Day on September 15 (United Kingdom);

Cry of Dolores or Grito de Dolores in Mexico on September 16 (Shout of Dolores is celebrated on the eve of Independence Day);