Quote Originally Posted by William F. Owen View Post
There is some compelling sets of data that show, except in open desert, average rates of advance since 1918 are < 2km per hour, and often substantially less. 30km per day is considered good.
Average and median are really of little interest.

A WW2 armoured corps with 40 km/h tanks* advanced 400 km in quite exactly four days- against the opposition of several conventional divisions in suboptimal tank terrain (Manstein's Corps to Vilnius).


Advance through defence is of little interest today in general. There are enough gaps for advance, and no continuous line of defence. You don't need to advance through deep defensive positions in most conventional warfare scenarios.
You can - if you prepare well for it - rather go back to an extremely accelerated version of Central European 18th century army maneuvers (Wars of Silesia as examples).
Speed of advanced in defended terrain was irrelevant then and it is (almost) today.



*: (that needed maintenance every hour of driving in order to prevent excessive breakdowns)