Hey guys i'm nearly upon finishing my first "campaign" (?) and i decided i'd wander off to war. So i have a few questions, and i would appreciate the help :)

 1. is why are my longbowmen actually shooting peas? i suspect its because i am a noob and don't yet understand how line of sight works or something, but they're constantly hitting for like 6-10 damage against similar units, as in units that are from the same era if not earlier. 

2. what in god's name happened to my pikemen? i have two or three of them in a little stack and we start a battle against one elephant (not the Mughal one idk the name of it the earlier one), and it's completely destroying my pikemen, like it could two shot them on both offense and defense, this is on flat ground and i read the numbers that go into its strength and its not that much stronger, like two or three points maybe, and yet it just cuts through my pikemen and even one-shots them if they're out of position. Coming from tons of hours on civ its mind blowing to me that an "anti-cav unit" can just get completely destroyed by a cav unit that is only a couple points stronger than it, is one or two points just that important in this game or am i doing something horrendously wrong? Because i read the numbers and i see the bonuses and negatives but like really? two shotting a pretty equivalent unit? I think my positioning and tactics are pretty good but they're just completely destroying my troops and i don't get why. 

Thanks for any help, like i said i come from civ so a lot of this is pretty familiar but combat has really confused me, its been a while since i've felt like such a noob :)

Line of sight absolutely matters. If your longbows don't have LoS, they'll do a lot less damage. Try to get them on the high ground to get a bonus to their combat strength as well

The Carthaginian elephant also gets a combat bonus when fighting weaker units. I believe it has a 36 strength while pikemen are only 31 strength so it will absolutely wreck them. Carthage is one of the strongest cultures to go against.

Also note in this game, you don't want to defend on a river tile. You get a combat malus if your unit is on a river when attacking/defending unless the enemy is also coming from a river tile