What is the Date of attack of the ship with iron ore sunk by u-101 *?
CREATE TABLE "merchant_ships" (
  "name" text,
  "flag" text,
  "cargo" text,
  "fate" text,
  "date_of_attack" text
);
SELECT "date_of_attack" FROM "merchant_ships" WHERE "fate"='sunk by u-101 *' AND "cargo"='iron ore';