How is the Owl Creek Bridge significant to the narrative?

The bridge is important to the story for many reasons, including the following:
The bridge is the target, the objective, the bone of contention. It provides the motivation for the protagonist, Peyton Farquhar. Momentarily it seems to be the focal point of the entire Civil War.
Farquhar is being hanged from it because it is the most simple and convenient place for a hanging. A hanging requires a certain elevation, which the bridge easily provides.
The bridge is also the most conspicuous place for the ceremony. Every soldier can see it from wherever he is stationed.
Farquhar is being hanged because he tried to burn it down. It is ironic that he is being hanged from the bridge he tried to burn down and that he is being hanged for trying to burn it down.
The bridge exists because of the creek. The creek enables the prisoner to seem to escape in the following ways:
The water seemingly revives him when he falls into it, and he is able to evade the rifle bullets by swimming under the water.
The creek is flowing very rapidly, which seemingly enables him to get swiftly carried out of gunshot range.
There is a lot of water in the creek at this time of year. This is helpful to the escaping prisoner. It also explains why there would be a lot of driftwood piled against one side, tempting him to set it afire in the first place.
Farquhar does not really escape, but the sight of the rushing water helps to create the hallucination that he falls into the creek and is quickly carried downstream to safety.
Although Farquhar seems to make it all the way back to his plantation and into the waiting arms of his wife, the story ends back at the bridge:
Peyton Farquhar was dead; his body, with a broken neck, swung gently from side to side beneath the timbers of the Owl Creek bridge.