A common mechanic in strategic war games is the gaining of additional production and/or ability to support an army after capturing enemy territory. The rationale for such rules (besides making the game more enjoyable and directed) is presumably that access to additional resources, facilities, soldiers, and workers could potentially boost the war effort.

But how does this potential gain balance against the increased resources required simply to maintain additional territory and the time taken to exploit any newly acquired resources? It seems to me that in many cases it would take years (i.e., longer than the war itself) to implement the necessary infrastructure to reap any such benefits, especially if the invaded country's infrastructure is damaged by the invasion. Are there specific examples of military gains in modern times due to the acquisition of new territory?