How did fighting on multiple fronts (in different places) affect the countries at war?

The correct answer to this open question is the following.

Fighting on multiple fronts (in different places) affect the countries at war in that they need to invest money, soldiers, and resources in two fronts, instead of concentrating on just one and support it 100%. AS the war is fought in two separated geographical places, the military has to split strategies and supplies in those fronts and it costs a lot of money, human resources, and material resources.

For instance, during the Napoleonic wars, France fought on two or more fronts. During World War 1, Germany open two fronts in fighting Russia in the Eastern front and France, Britain, and Belgium -and later the US- in the Western front.  

the hyksos invasion. the hyksos were able to attack egypt successfully because of their skills in using bronze weapons, composite bows and the use of the horse and chariot during the invasion. although the egyptians depict a barbarian-type overthrow, the truth is the seizure was likely a relatively peaceful one.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.