Rep. Nancy Mace announced a major loss in her family ... she took to social media to announce her father, Gen. James E. Mace, died Tuesday night.

The South Carolina congresswoman shared a lengthy tribute to her father, posting a pic of him in his military gear and describing his final moments in the caption.

Nancy said her dad was surrounded by his wife, two of his daughters -- Nancy and Mary -- and his two dogs.

The politician said her dad passed as she read him testimony of the soldiers he served with, writing ... "As I read those words to him, he grew calm. And then he was gone."

She also mentioned that he died the same day as one of his grandson's birthdays, noting ... "God doesn’t do coincidences. He chose this day on purpose. A life celebrated as another began."

Nancy also posted on X that she's "heartbroken" by the loss, but claims it showed her "God is real."

She wrote ... "Today unfolded exactly as He intended. And it was nothing short of a miracle."

He was 85.

RIP