In ancient Latvia, Māras or Māras diena (also Lielās Māras diena or Mātes diena) was a festival, celebrated on August 15, held in honor of Māra, the Latvian goddess. It marked the midpoint between Jāņi (the summer solstice in June) and Miķeļi (end of harvest season).
This festival celebrates the end of the harvest season and the end of the summer, but also the death of the ancestors. This festival is related to the Japanese Obon or Bon_Festival, also being celebrated on 15th August. This festival was taken over by Christianity where the Mary was identified with Māra whose main festival (Assumption) falls on the same date since antiquity.