30 Ağustos Zafer Bayramınız kutlu olsun.

August 30 was the day on which the Turkish lands were entirely cleared from the enemies.

I used to think that. But isn´t 30 august the date of the Battle of Dumlupınar, which wasn´t the final victory, but an important one of the final victories. A lot of cities celebrate "kurtuluş günü" for days after this date e.g. İzmir it took until early September for it to be completely Turkish.