Greatest and most effective military tactics and strategies?

Mar 2016
877
Australia
#2
Scorched earth has generally done pretty well at stopping numerically superior forces invading a country, as much as it causes great destruction and suffering for the common people.
 
Oct 2011
109
Croatia
#6
Byzantine implementation of Fabian strategy against the Caliphate. They would retreat into forts, and let the Caliphate forces plunder the countryside - which turned out useless anyway, since economy of Asia Minor was based on the animal husbandry, and unlike crops, animals have legs.

A lot of Byzantine strategy was actually based on the experiences of Emperors Maurice and Heraclius. Relevant:
https://digitalcommons.iwu.edu/cgi/viewcontent.cgi?article=1094&context=constructing