Crossbowmen slaughter my Mech Inf?

[The Snug]

I thought they said that spearmen wouldn't be able to kill tanks.

It took me like 20 turns to build the damn thing (on normal speed), another 20 to get it to my enemy, only to watch it get smacked by a bunch of crossbowman, and a city tower, and then die to some iron melee unit. What gives?

 

[boredatwork]

I fail to see the problem? A crossbowman isn't armed with a spear and an Infantry Fighting Vehicle isn't a tank.