CREATE TABLE table_24394 ("State  ( class ) " TEXT, "Vacator" TEXT, "Reason for change" TEXT, "Successor" TEXT, "Date of successors formal installation" TEXT)

What change caused a change of staff in March 9, 1865?
SELECT "Reason for change" FROM table_24394 WHERE "Date of successors formal installation" = 'March 9, 1865'
SELECT "Reason for change" FROM "table_24394" WHERE "Date of successors formal installation" = 'March 9, 1865'