CREATE TABLE table_18022 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Game site" TEXT, "Record" TEXT, "Attendance" FLOAT)

On what date was the game against San Diego Chargers played?
SELECT "Date" FROM table_18022 WHERE "Opponent" = 'San Diego Chargers'
SELECT "Date" FROM "table_18022" WHERE "Opponent" = 'San Diego Chargers'