Overboard

From BoardGameGeek:

This game is one of a series of 2 player strategy games by Lakeside from the 1970's, also including Blockade, Trespass, and Isolation. In Overboard, the "Slide to Survive" game, the board is a 7x7 grid of squares with slots between them to create a grid of 6x6 or 36 playing positions. There are 36 pieces, 18 red, 18 white, which are placed on the intersections between the squares; they have little knobs which hold them in the slots. On his turn, a player uses one of his pieces to push a row of his opponent's pieces off the board, a la Kuba. The winner is the last player with pieces on the board.