Identify board game with a castle divider, air plungers, soldier-shaped plugs?
I think you might mean Battleboard.  I found it typing "air plungers board game castle" into google image search

According to information on BGG it was from 1972. It is a two player game.

The photos fit your description of being green with a castle.

the description says :-


  Each player has four knight pieces and one king piece. At the
  beginning of the game they are placed in the row furthest from the
  dividing wall. Players take turns moving one of their pieces one space
  (orthogonally). They then get to use their "air catapult" to try to
  pop out one of their opponent's pieces. This is done by placing their
  plunger in one of the vacant spaces on their side of the board and
  then banging it. If their opponent has a piece in that corresponding
  space, it will pop up into the air. Pieces captured in this way remain
  out of the game until that player moves his king up to the dividing
  wall, at which point he can claim a captured knight piece back (but
  also tips off his opponent that his king is in the front row). The
  first player to move two pieces into the front row (next to the
  dividing wall) wins the game.