The Mark IV

"That's what I want!  That's what I want to have."

-- Adolf Hitler upon seeing a tank demonstration

My Martian colonists need a tank.  But not just any tank.  They need a tank that looks like it was built, hastily, for use against the Ancients, by people who've never used a tank in battle before, and who have (at best) 1930s-ish technology.  I want something big, clunky, covered in rivets, and generally odd-looking.  So I need to avoid the more familiar hull-shapes of WWII - no Shermans, or Tigers or T-34s.

Here's the first candidate for the job: a British WWI Mark IV from Old Glory.

The model comes with two sponson options: either side can have a cannon or machine-gun.  (WWI trivia: a tank with cannon sponsons was "male."  A tank with machinegun sponsons was "female."  I guess machineguns are soft and feminine? A tank with one of each is a "hermaphrodite.") I assembled a male tank.

As a tank for my Martian Colonists, it certainly fulfills several aesthetic requirements.  It's clunky and weird looking, for sure. It's got lots of rivets.  On the other hand, it is somewhat small.  I am surprised at how tiny it actually is. In pictures from WWI, the Mark IV looks like a Winnebago with machine-guns.  In actuality, it's about Sherman-sized.

Another issue is the cannons.  In real history, early tanks had small calibre guns because they did not expect to fight other armored vehicles much. Their envisioned role was as an anti-infantry instrument. Hence, the rapid increase in size and velocity of WWII tank armament, and the related increase of their armor, once they started actually fighting each other.

In my universe, the Colonists invent tanks as a way of fighting the Ancient's war machines.  So they are likely to put the biggest gun they can onto the chassis. The Mark IV's guns look pretty dang wimpy to fight alien war machines.