The trench system was also based on World War I principles.

Another trench system used by al-Shabaab was discovered and destroyed.

Once they came to the rear of the trench system, the motor-car could advance no farther.

They entered the trench system, sinking lower into the ground, and the water came up to meet them.

He came out of the 270-degree turn running parallel to the trench system.

Both bridges had sandbagged trench systems along the banks.

In the 1990s an original British trench system was discovered by amateur archaeologists, on the site of an industrial estate near the village.

A single trench system was relied on for defence.

The Filipinos withdrew to a secondary trench system, but were soon driven from that also.

They also allowed for troops' easier movement through the trench systems.