Skirmishers out-ranged my TC?

I just played a Hard AI 1v1 on Gold Rush, Japs vs Slavs, and my forward TC got taken out by skirmishers and archers... I had 8 vills garrisoned but they weren't able to attack the enemy units, only their melee ones. When I directed the TC to attack the skirmishers, I got the "out of range" error but I clicked on them while they were attacking. I looked up the ranges and they shouldn't able to do that, right? It's 5 range vs my TC's 6, and the Slavs don't have any bonuses for their range either... They were uphill but from everything I looked at online that should only affect the damage, not the range! What is going on?
 
TL;DR: title.