Why is this the answer?

The answer is pawns because this clever riddle is describing the smallest but most important pieces in the amazing game of chess. Think about a chessboard. It is set up like a battlefield for tiny, tiny warriors made of wood or plastic. When you first start a game, each player has exactly eight pawns. These eight pieces line up right in the second row, standing in front of all the bigger, stronger pieces like a strong and brave wall. The first line of the riddle says, "The eight of us move forth and back." This gives us two great clues. First, it tells us the number eight, which is exactly how many pawns you have. Second, it talks about their special movement. Pawns are the only pieces that usually move straight forward, one step at a time. They are the first to move "forth" into the battle, trying to cross the board. They cannot jump backward like other pieces. They move forward to fight the enemy. This forward movement is very important to the entire game. Also, even though they move straight forward, they only capture an enemy piece by moving one diagonal step forward. This can feel like a tricky back and forth dance with the enemy as they fight for control of the board. The second part of the riddle says, "To protect our king from the foes attack." This is the pawn's most important job. The king is the biggest treasure in chess. If the king gets captured, the game is over and you lose. The pawns are the loyal, brave soldiers who stand in the front line. They take the first hits and face the danger so the other pieces and, most importantly, the king can stay safe behind them. You could say that your eight pawns are the bodyguards that the king relies on the most. They work together as a team to keep the entire side protected, showing that they are small in size but mighty in purpose.