As has been touched on above, abandoning your major population centre, strategic stronghold and most defensible proposition is rarely a victorious tactic.
In addition and in response to the above 'slash'n'burn' proposal, it is worth noting that this is a truly horrific tactic that any force controlled by a power with concern for the welfare of life and lands would avoid at all costs. To delve further into the example of the Russian withdrawal through these means during WWII, the scorching of the rich farmlands of the Ukraine and then-western-Russian provinces caused the death of, conservatively, several tens of millions of people, and plunged those lands into a cycle of poverty and hardship from which some areas have barely recovered. Some victories are not worth having.
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And all the rest is literature
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