Tomorrow's bayram

Tomorrow there will be planes flying in formation over Baku, with the 3 colors of the flag streaming behind them. But what is this bayram called? It's known by two names. Both are a bit difficult.

Silahlı qüvvələrin yarandığı gün
And
Ordunun yaranması günü

But most people say: Ordu günü

Much easier to say and remember.