What is the namesake of the ship that was commissioned or completed(*) 16 april 1864?
CREATE TABLE "ships" (
  "ship" text,
  "builder" text,
  "namesake" text,
  "renamed" text,
  "laid_down" real,
  "launched" text,
  "commissioned_or_completed" text
);
SELECT "namesake" FROM "ships" WHERE "commissioned_or_completed"='16 April 1864';