Here's an image:




Basically, I don't have enough troops to attack the blue space, but I have enough to protect. What's the lowest amount that I can put on my space to protect against blue, assuming blue doesn't add any more to it and how can I figure this out in the future? Is there a formula?

The built in analyze function can be used to determine this for your map's settings. There is no way to definitively give an answer without knowing specific game settings

It depends on the luck. Check Analyze Attack to see the percent chance of how many will be able to take that territory.

attacking armies*0.6 + 1 and then you do the rounding

EDIT: this works for 0% SR

Edited 5/1/2015 02:51:11

You need to give us more information. Game settings: luck, 0 or higher? Straight round or weighted random? Also, is it no-luck cyclic move order? And finally and perhaps most importantly: what's his income?

Edited 5/1/2015 03:36:41

Is it an AI or a human? AIs wouldn't deploy much more armies on Panama, humans would.

18 kills 11 in 0 luck SR games in which offensive killrate is 60%(standard killrate)
if he's not deploying,he'll attack with 18 since he has 19 on your border and 1 will remain behind in central america
12 can defend barely against 18,but they'll kill only 8 while defending,so overally you still face a loss of 3 armies more than your opponent
defending with 15 gives you 11 kills which will equallize with your opponent
defending with any more than 16(i.e.17,18,...) will be beneficial for the defending armies as you'll kill more than your opponent kills yours

extra pro stuff:-many a times players deploy around double the armies than their opponents and attack them in hopes of killing their armeis,this is not the most efficient way to beat a low levelled player
suppose your opponent has 19 armies and you KNOW he can't attack with anything more than 18 and he's definitely going to attack you,you can actually take over his territory with just 20 armies
all have to do is make sure you ALWAYS get the last move after your opponent
in that case 18 attacks 20 and kills 11,9 remain,20 while defending kill 14,so 4 remain,those 4 armies go back since attack failed and 5 remain in the opponent's territory
so from your 9, 8 can attack him and kill 5 and you get the territory

this surprises many newbies since they think how did 20 killed 18 cause they always skip turn?
well now you know how :)