In the aftermath of the epic Wimbledon final between Andy (Not Murray) Roddick and Roger (thank goodness Nadal is hurt) Federer, a lot of sports journalists embarked on a mission to prove that Federer was the greatest tennis player of all time. But for some of the journalists that just wasnt enough. In fact on BBC Sport writer decided to compare Tiger Woods and Roger Federer, trying to decide which of these two fabulous sportsmen is the greatest.

Even as I was reading the article I found myself prickling with irritation - how can you compare the sports, how can you exclude other fabulous sportsmen like Bradman, Schumacher, even the likes of Usain Bolt and Pele from the list? I was preparing myself for a classic 'internet rant'. But I was beaten to the punch. Below the article were reams of comments arguing the issue (some of them are rather humerous - have a read!).

But this all got me thinking. If you can compare two sportsmen in totally unrelated fields, you can logically compare military forces from different eras effectively. So which military force would I choose as the greatest military force of all time? Would it be the Romans for conquering most of the known world and changing the way war was fought? Or Alexander's armies? Or the rampaging forces of Gengis Khan and his successors? Maybe it would be today's US Army for their sheer technological superiority and superpower status? Or the Chinese army, simply because of its overwhelming man power? Could it be the SAS with their ongoing reputation as being the best trained special forces unit in the world? Or the Vikings for their ability to conduct seaborne invasions? Even less conventional forces could be viewed as a great force. The Viet Cong were able to defeat a vastly superior force.

So who do you think is the greatest military force of all time? And dont forget to show your working, we need a good reason for your selection. The person who has the best answer with the strongest argument will be rewarded with an Osprey book of their choice!