Gone with the Wind: Metaphor Analysis

Land
Land - or, to be precise, continued ownership of land - is a symbol of permanence in a fast-changing world. As Rhett remarks, Tara is the one constant love of Scarlett's life, and she comes to know the truth of Gerald's statement that "Land is the only thing in the world that amounts to anything." The reason she sets up her businesses in Atlanta is largely to support Tara. She marries Frank only to pay the taxes on Tara, so that she will not have to sell it. She feels personally insulted when Jonas Wilkerson and Emmie Slattery offer to buy Tara, so intensely does she identify with it. Indeed, the earth at Tara is constantly referred to as red, which is strongly suggestive of blood. It is as if this piece of earth is Scarlett's life-blood ("She could not desert Tara; she belonged to the red acres far more than they could ever belong to her. Her roots went deep into the blood-colored soil and sucked up life, as did the cotton." - Chapter 24). It is no coincidence that Scarlett forms her determination that she will "never be poor again" while lying on the bare earth at the ruined Twelve Oaks plantation. When Ashley rejects Scarlett's suggestion that they elope, he gives her a clump of Tara's earth and tells her that she loves Tara more than she loves him. Scarlett knows that he is right.
The fact that Scarlett, with Will Benteen's help, is able to bring Tara back into production after the war symbolizes her success at survival. Those plantation owners who fail to reclaim their wasted land are those who, in Ashley's words, have been "winnowed out," who will not survive. Thisis made clear in the scene in which Scarlett returns to Tara after the war and notes how, on other plantations, the weeds and trees are encroaching on previously productive land.
Swords
Swords are introduced to symbolize the courage and gallantry of the Old South, and are specifically linked with Melanie and her family. When the Yankee looter invades Tara, Melanie, who has got up from her sick-bed, appears at the top of the stairs dragging Charles' heavy sword. Despite the fact that she can barely lift the sword, she is prepared to use it in defence of Tara and Scarlett.
When Scarlett faces social disgrace after the revelations of her embrace with Ashley, Melanie becomes her sole defender. Melanie is likened to a sword, perhaps because despite her thin outer form, she is possessed of inner steel: ".Melanie standing between her [Scarlett] and social ruin, standing like a thin, shining blade, with trust and a fighting light in her eyes." (Chapter 55).
Characters as symbols
Rhett and Scarlett symbolize the New South, nostalgically looking back to the old days but prepared to do adapt and do whatever it takes to build a prosperous life amid the depredations of the war. Rhett's shifting allegiances (he allies himself with the Yankees when it suits him and reinvents himself as a Southern Democrat when it seems expedient) symbolize the rapid changes to which the South had to adapt in order to survive.
Melanie and Ashley symbolize the Old South, the honorable yet frail ones who are "winnowed out" in the harsher post-war climate, though Melanie proves far more able to face reality than her husband.