Aughrim was 12 July 1691, old calendar: add on 10 days for equivalent modern date = 22 July.

Boyne fought on 1 July 1690, old calendar: equivalent modern date = 11 July. ("the 12th" is a miscalculation, should be the "11th", due to Rome, and Catholic southern Europe, adopting new calendar in 1582 and suspicious Protestant Britain not adopting the new calendar until 1752).

(I still don't know what point Larry is making!).