CREATE TABLE table_18048 ("Incumbent" TEXT, "Reason for Vacancy" TEXT, "Appointed Successor" TEXT, "Date of Appointment" TEXT, "Elected Successor" TEXT, "Date of Election" TEXT)

What was the election date for H. Brent Coles?
SELECT "Date of Election" FROM table_18048 WHERE "Appointed Successor" = 'H. Brent Coles'
SELECT "Date of Election" FROM "table_18048" WHERE "Appointed Successor" = 'H. Brent Coles'