CREATE TABLE table_1342426_18 (incumbent VARCHAR, candidates VARCHAR)

Who was the incumbent in the election of henry garland dupr (d) unopposed?
SELECT incumbent FROM table_1342426_18 WHERE candidates = "Henry Garland Dupré (D) Unopposed"
SELECT "incumbent" FROM "table_1342426_18" WHERE "Henry Garland Dupré (D) Unopposed" = "candidates"