CREATE TABLE table_204_353 (id DECIMAL, "no." DECIMAL, "date/time" TEXT, "aircraft" TEXT, "foe" TEXT, "result" TEXT, "location" TEXT, "notes" TEXT)

when was the last battle ?
SELECT "date/time" FROM table_204_353 ORDER BY id DESC LIMIT 1
SELECT "date/time" FROM "table_204_353" ORDER BY "id" DESC NULLS LAST LIMIT 1