Another thread has noted that she died on the 13th of the month. The Fatima equivalent of 7/4/1826 for those seeking the approval of the Almighty!
I just tried to do a Google search to discover what calendrical reckoning you use to get the date '7/4/1826,' but I came up blank.
2005-February-13 corresponds to 5765-Adar Aleph-04 in the Hebrew calendar, 2005-January-31 in the Julian calendar, 1426-Muharram-04 in the Islamic calendar, 1721-Amshir-06 in the Coptic calendar, 1997-Yakatit-6 in the Ethiopic calendar, 0161-Mulk-07 in the Bahai calendar, 1926-Magha-24 in the Indian civil calendar and 1383-Bahman-25 in the Persian calendar. But none of those correspond to 1826-07-04.
I am sure I remember reading that the Blessed Mother told Lucia not only that Francisco and Jacinta would die young but that she would live to see the end times. This must be it.