Why was the breaking of the wall of Helm's Deep so important in "The Two Towers" movie?

Question

I have not read the book, and I am referring here to the movie only.

I saw in the movie that the way that lead to the inside of Helm's Deep was through a gate, from a somewhat steeply inclined ramp; both the gate and the ramp were not directly connected to the wall, that was built on another side of the keep.
So, the way inside the Helm's Deep didn't go through the wall. All I could gather was that you could place people, on and behind the wall, for defence/attacking. But that can also be done from the roof of the fortress (which was done too, obviously).

So, why this line by Saruman:

"If the wall is breached, Helm's Deep will fall!"?

and we see that it nearly fell, too, in the movie. Does the existence of the wall somehow prevents the breaching of the gate? If yes, then how?

Answer 1

The whole fortification complex at Helm's Deep was not only meant to defend itself, but also, and mainly, to protect the whole valley from external threats.

Technically speaking, Helm's Deep was the name of the valley where the Hornburg, the actual fortress, was built. The fortress itself was comprised by the proper stronghold and by a connected wall (the Deeping Wall) that completely closed the access to the valley. Here you can see a couple of maps of the whole area, that can help you understand the importance of the whole fortification complex:

_{From The Atlas of Middle Earth, by Karen Wynn Fonstad; faithfully based on a sketch by Tolkien himself, depicting the whole area:}

and

_{From Beoner on DeviantArt; based more on the movie depiction rather than the original view by Tolkien as on the books}

As you can see the Deeping Wall entirely closed the access to the valley leading to Glittering Caves of Aglarond; because of this it was a very important part of the whole fortification for many different reasons:

• from a tactical point of view, it prevented the Hornburg to be sieged from all sides; with the Wall standing, it could not be completely encircled, the rear gate was not exposed and there was no need to man it, making the whole keep more easily defended (they should only defend the front and not the rear side);
• from a strategical point of view, it served as the main guard and gate for the Glittering Caves, that were said to be used also for stockpiling livestock, food and presumably other necessary goods during a siege; losing the Wall also meant losing the Caves; when you have lost your supplies during a siege, you have lost the siege itself;
• from a "humanitarian" point of view, the Caves were also used as an extreme refuge by the Rohirrim people during the harshest times of war. They were a shelter for civilian people making the whole fortification complex at Helm's Deep very important not only for military purposes. The Hornburg itself could probaly stand on its own for a limited amount of time after the fall of Deeping Wall, but the Caves were immediately in danger: all of your people would be suddenly threatened and without defence.

Answer 2

The Deeping Wall protects the Deep behind the Keep, this is the only escape for the Defenders

What you seem to be misunderstanding is the layout of Helm's Deep. The Wall, defended the actual "Helm's Deep" The space we can see middle of the picture between the two rocks. The Hornburg, the castle you seem to think they're talking about, is impenetrable, but less so once you've taken the wall, and the deep behind it.

At Helm’s Gate, before the mouth of the Deep, there was a heel of rock thrust outward by the northern cliff. There upon its spur stood high walls of ancient stone,and within them was a lofty tower.

The wall was what stood between that armies and Helm's deep, as the Hornburg was inpenetrable. Once the wall falls, the Hornburg becomes completely surrounded and the attackers now have full strength to enter the Deep (the cleft between the rock, behind the Hornburg). Saruman is identifying that once the wall is destroyed they have access to the deep. This doesn't mean the Hornburg is lost, but at this point, Theoden is surrounded entirely.

There was a side door in the film, which could be accessed from the wall.

From the film's point of view, there was a staircase that led to a Sally Port in the Fortress. The breaching of the wall would allow the orcs onto the wall and access to the Sally port. This would give them another point of attack into the Hornburg, although at this point they've taken the Deep already.

_{The staircase can be seeb on the right-hand end of the curtain wall and on the left of the Keep}

_{Tolkien's drawings of Helm's Deep and the Hornburg}

Answer 3

It's kind of hard to see but in this picture you can see a ramp from the inside of the Deeping Wall up to the Hornburg (circled in red to help make it easier to see the guys with torches running up the ramp). While not entirely movie canon, any of the LOTR games that have Helm's Deep do not have another gate at the top of this ramp, merely an archway that you can run through. Losing the Deeping Wall means that there is now an open doorway for the Uruk-Hai to get to the heart of the fortress.

Answer 4

It literally means just that. Should the walls of Helm's Deep fall, Saruman's Orcs would be able to enter. The fortress itself has the reputation of never falling into the hands of the attacker.

'I have still this to say,' answered Aragorn. 'No enemy has yet taken the Hornburg. Depart, or not one of you will be spared. Not one will be left alive to take back tidings to the North. You do not know your peril.'

---

The scene where Saruman says just that is where he's making a "bomb" of sorts to breach the wall. The gif below shows what he was intending to do:

In the books, this is what happened when the wall was "breached":

Even as they spoke there came a blare of trumpets. Then there was a crash and a flash of flame and smoke. The waters of the Deeping-stream poured out hissing and foaming: they were choked no longer, a gaping hole was blasted in the wall. A host of dark shapes poured in.

'Devilry of Saruman!' cried Aragorn. 'They have crept in the culvert again, while we talked, and they have lit the fire of Orthanc beneath our feet. 'Elendil, Elendil!' he shouted, as he leaped down into the breach; but even as he did so a hundred ladders were raised against the battlements. Over the wall and under the wall the last assault came sweeping like a dark wave upon a hill of sand. The defence was swept away.

And indeed, without the timely arrival of Gandalf and Eomer (Erkenbrand in the books), Helm's Deep would definitely have fallen.

Answer 5

In real scenarios keeps, castles and strongholds are built to take advantage of natural defend-able locations that provide for those seeking to defend themselves with some necessary commodities and advantages in a battle, such as, storage locations for food, fresh water, fodder for horses and other livestock, difficult to scale mountains limited attack from most sides. A promontory provides difficulty for attackers and vantage point to observe attacking forces as well as a projectile platform, to allow transport of food, water and other resources into the fortress side entrances behind the Deeping Wall would have been necessary. Once breached the main fortress would be limited for food and water as well as attackers finding it more easily accessed than through the main gate.