1、The trench lines of the Petersburg–Richmond theatre of operations in the final months of that war were the foremost example of trench warfare in the 19th century.
2、The typical trench system in World War I consisted of a series of two, three, four, or more trench lines running parallel to each other and being at least 1 mile (1.6 km) in depth.
3、He drew Honor to a halt at the edge of the moat, a deep trench lined with stone, its green waters choked by scum.
