CREATE TABLE table_28720 ("Monarch" TEXT, "Heir" TEXT, "Status" TEXT, "Relationship to Monarch" TEXT, "Became heir; reason" TEXT, "Ceased to be heir; reason" TEXT, "Next in succession" TEXT)

Who is the monarch when became heir; reason is 13 july 1783 father succeeded?
SELECT "Monarch" FROM table_28720 WHERE "Became heir; reason" = '13 July 1783 father succeeded'
SELECT "Monarch" FROM "table_28720" WHERE "Became heir; reason" = '13 July 1783 father succeeded'