The phrase "a system of trenches" is correct and usable in written English.
It can be used when describing a network or arrangement of trenches, often in a military or engineering context.
Example: "The soldiers dug a system of trenches to protect themselves from enemy fire during the battle."
Alternatives: "a network of trenches" or "an arrangement of trenches".
Once these objectives had been captured, they were to advance and capture a second system of trenches defending Et Tire without artillery support, as the guns would be out of range and in the process of being moved forward.
In the Battle of Dien Bien Phu (March 13 May 8 , 1954, which resulted in the French expulsion from Indochina, the communist-led Viet Minh used classic 18th-century siege methods and drove forward an elaborate system of trenches to negate the effects of French artillery and airpower, preparatory to the battle.
Maj Gen Gary Volesky said Isis was burning its forward positions outside Mosul and withdrawing to make a stand behind a system of berms, walls and trenches.
MOGADISHU, Somalia — At least 20 people were killed and dozens wounded in heavy fighting in Somalia's capital over the weekend, as African Union forces attacked an extensive underground fortification system of trenches and tunnels used by Islamist insurgents.
In October 1918, this area - around the village of Ramicourt - was the Beaurevoir-Fonsomme line, part of the Hindenburg Line system of trenches, fortified villages and gun emplacements that formed the last line of German defences on the Western Front.
On their right, the main Tabsor system of trenches held by the Ottoman XXII Corps was attacked and eventually captured during the Battle of Tabsor, by the 3rd (Lahore), 7th (Meerut), and the 75th Divisions.
Other Ottoman outposts at El Kossaima and Nekhl remained, along with their strong defensive system of trenches and redoubts at El Magruntein, defending Rafa, on the frontier between Egypt and the southern Ottoman Empire.
The Challenger Deep and similar recesses are part of a vast system of seabed trenches that crisscross the globe.
