Breastwork (noun)

1. A defensive wall or barrier, often made of earth or stone, built to protect a position or stronghold.
2. A temporary fortification or barrier, used especially in military operations.

Origin:

From the middle english breast + work, meaning a work or fortification built across the breast or chest.

Examples:

1. The soldiers built a breastwork to protect their position from enemy fire.
2. The breastwork was used to defend against the enemy's attack.
3. The soldiers used the breastwork as cover while they reloaded their weapons.
4. The breastwork was crucial in preventing the enemy from capturing the stronghold.
5. The breastwork provided the soldiers with a strong defensive position.