Merican Military History: Total vs. Limited War

The Civil War and WWII have often been the benchmarks by which American wars are compared and judged. They were both big wars with fixed lines, conventional tactics, and distinct battles.

Vietnam, on the other hand was a fluid war with no fixed lines, with use of guerrilla or unconventional tactics and few fixed battles.

Considering the entire scope of US Military History, and using Vietnam as a main example, do you think the US has engaged in more WWII (i.e., total war) or more Vietnam (i.e., limited) type wars?

What kinds of wars should the US prepare for in the future?

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