CREATE TABLE table_18451 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

In what year was John Bell Williams first elected?
SELECT "First elected" FROM table_18451 WHERE "Incumbent" = 'John Bell Williams'
SELECT "First elected" FROM "table_18451" WHERE "Incumbent" = 'John Bell Williams'