Losing a territory with 5 defending army from 6 invading enemies under 16% luck. How?

http://warlight.net/MultiPlayer?GameID=4528699 , final turn.

I have calculated that his max invading army is only 6 unit that turn. So I made sure my adjacent territories have at least 5 defending units to be secured. However I was wrong.

He splitted attack using 4+2 and captured my territory which has 5 defending units.

So my question is: is this a common strategy used by skilled players? Is splitting army to invading a territory gives you a higher success rate?

Um, on those two orders he had a luck swing of like 2.3. Those orders don't make any sense, he just got really lucky.

If you need to take a territory and you have two stacks already deployed, one of 10 and one of 15, say, you might deploy to the larger stack, and then attack the territory with the 10 first, and then attack with the large stack. That's common.

But he deployed all those armies on the same turn, and he attacked with the larger one first, which is wrong. I'm not really sure what he was trying to do, I guess he was trying to complete the bonus while still defending those two territories.

question 3: why should we attack with smaller stack before larger stack?

question 4: so when we want to use 6 units to invade a territory with 5 defending units, we should try to split attack with 2+4 if possible?

Well i'm surprised as well as you, but math says there is 40% chance that 4 attackers kills 3 defenders and 12% that 2 attackers kill 2 survivors - so it gives almost 5% chance for success when attacking with 4 and 2. In opposite - there is 0% chance for 6v5 win (it's probably more than 0 but still very little). I suppose that is because with two attacks luck gains bigger impect.

Is splitting army to invading a territory gives you a higher success rate?

i would say - only if chance for success for attacking with all is very small.

If you're attacking a territory with 6 armies, you shouldn't be expecting your opponent to have 5 armies there.

Question 3: That gives you a better chance of taking the territory. Someone ran the numbers on that a while ago.

Maybe it's better to attack with like 1, 1, 1, 1 and 2, than 4 and 2. But it's so pointless because if you're making gambles like that then you should just be surrendering.