When considering how Lewis’s wartime experience might have affected his depiction of conflict in Narnia, a more physical comparison presents itself when turning to the question of fortifications in Narnia. While most often thought of as residences for the various personalities of the world, they are also intended to serve a more militant purpose. Cair Paravel, Jadis’s Castle, Anvard, the small towers Tirian, Jill, and Eustace use in The Last Battle are all designed to be comfortable and yet are also strong points from which Narnia and her allies can defend their lands. Viewed from the general context of the Great War, it is interesting that Narnians exhibit a peculiarly British attitude towards fortifications and their use. Unfortunately, in all but one example, they have reason to regret this.
During World War I, the Germans tended to build more complex trenches and then wait for their opponents to come to them. They could afford this luxury since, as they occupied French territory, they could expect their enemies to attack in an attempt to drive them out. The Allies, on the other hand, tended to take less care in trench construction for the simple reason that they never planned to stay in them long. British General Haig remained fixated on restoring movement to his army, believing that each new attack would be the one to break the German line. As such, British trenches were often less complicated and less well equipped. While the Germans hauled in tons of concrete and steel and wired their trenches for electricity, the British (and to a lesser extent, the French) tended to make do with the bare necessities and constantly came out of their trenches to attack their enemies.
There could hardly be a better general description of Narnia’s construction and use of her strongholds. A number of them are rather simple in design and exhibit none of the post-crusades refinements of the high middle ages. While readers are not given much information on the specific defenses of Cair Paravel, both Anvard and the Witch’s Castle lack even a moat (In Jadis’s defense, a frozen moat would do little good, but a dry moat would be practical). While these oversights cost the Witch in her war with Aslan and Cair Paravel in its last defense, Anvard is able to survive by the timely arrival of reinforcements. Had Edmund’s army been delayed, the lack of a more in-depth defense would have allowed Rabadash and his force of Calormens to batter down the gate with little more than a tree (The Horse and His Boy 178-179).
This lack of strong fortifications seems to have been due to the fact that, like the British, the Narnians preferred the offensive when provoked. Narnians—good and evil—very rarely actually fight from behind their prepared works. They are constantly coming out of them and fighting in the open, where their defenses do not benefit them in the least. While Aslan thinks that Jadis might withdraw to her castle to face a siege in The Lion, the Witch, and the Wardrobe, she actually attacks Peter’s army directly. As a result she loses when reinforcements are freed from her undefended home and overwhelm her in a sudden rush (164-176). In Prince Caspian, while Dr. Cornelius talks at length about the defensive advantages offered by Aslan’s How, once Caspian’s army occupies it he repeatedly launches sorties to attack Miraz’s forces on open ground, where the Telmarines obviously have the advantage. The battles usually end in stinging defeats for Caspian, who eventually relies on Aslan and an army of reawakened trees for victory(85-93). Only at Anvard in The Horse and His Boy do the defenders actually put their advantages to good use, and even there they emerge from the castle walls to go on the attack at the first opportunity (175-185).
Lewis himself never explained his reasoning on the issue, and so it is now impossible to push this claim to an absolute conclusion. To do so would be to fall into the age-old trap of biographers who somehow think that they know their subjects better than their subjects knew themselves. Yet, there is a strong correlation between the way Lewis’s own people utilized their trenches in the war in which he participated and how the Narnians themselves used their closest equivalents. In this, the Narnians seem to be distinctively British, as indeed Lewis was himself.