i started last week but with some gameplay of both roles and some dedication watching good streamers it was easy to get in to it <| sep |> Basically , to declare war , you need something called a claim . Claims show up in the character screen the one with a roundy avatar in the second lowest line . They come in 2 varieties weak just the coat of arms of the realm or strong a CoA with a green outlier . Strong claims are much better than weak ones , because you can press them aka going to war as soon as possible , while weak ones have some prerequisites . Always hover your cursor over the claim to see if its inheritable or not you want the inheritable ones , unless you know you can press the noninheritable one soon . To get a claim , you can invite someone with a claim use the character search keybind . to find someone with a claim . They ' ll show up with little crowns in the search , near their avatar if you land them before you press their claims or at least before winning the war , as long as the claimed title is lesser than yours i . e . if you ' re a duke , never press duchy claims for others only counties ! , they ' ll stick as your vassals . marry someone with it and then press it . Your spouse will get the lands , but your heir will too when she dies . Again , watch out if the title is equal or higher than yours she ' ll become independent if it is ! marry someone with it , killlet she die and press the claim of your heir . He ' ll get it as soon as you win . It ' s much safer , but slower , than the first option . You can , of course , wait for you AND your spouse to die , so you ' ll get to press the claim AS the heir landed heirs usually make a lot of bad decisions , so it ' s not always good to land them . As long as you have a better succession law than Elective Gavelkind , it ' s safe to press this one even if the claimed title is equalhigher than yours . fabricate it with one of your Chancellor ' s missions in the council . This one will cost money and prestige you ' ll get piety if you don ' t accept the fabrication , but will give you a noninheritable strong claim don ' t use this option if you ' re sick or old ! If your Chancellor is good enough high Diplomacy , you can even try to fabricate a claim on an entire duchy ! If you have Become King of X ambition and you put your chancellor at the capital of said kingdom , he can fabricate a claim on the entire kingdom . if you have a title but not its all de jure lands , you ' ll be able to war those people with them , but just a county at a time . you can try to get you independence from your liege either faction or direct declaring . This is much safer if you can get many people with you or you ' re already so powerful that you don ' t need them . You ' ll become the liege of those that support you until you win the war . you can start a faction to substitute your liege with someone else and that else can be you ! . You ' ll become the liege of those that support you until you win the war . ask for your head of religion to excommunicate a realm owner , giving you the rights to attack himher . The head of religion must like you more than your target for this to happens . if neighbor 2 sea zones away from someone with a different religion groupheretic , you can declare holy war . Holy war gives you an entire duchy , wipe clean but people from the same religion of the target will mostly help himher ! if you ' re smaller than your target , but asmore powerful as she , you can ask your head of religion to let you invade the target . if tribal andor pagan , you get some different war methods conquest , prepared invasion , subjugation . you can war someone just to pay you some tribute tributary . This one is better if you are young , because when you die the suzerainty ends ! After acquiring a claim , you can rightclick the target and then choose one of the options to declare war for . Try to always choose the one most complete andor safe , because you ' ll get a 10 year truce with the target after you end the war winning or losing , and the prestige hit for breaking such truce can be steep . So , a holy war is much more complete than a single de jure claim , but it ' s much less safer it ' s pretty safe using holy war against a single , heretic county , but not so much if you attack a muslim duchy near many others . Before declaring war per se , check your troops and money . At the right side of the character screen , there ' s a small metal cap with a number . That one represents how many people you have under you , able to be called to war right now . Hovering the cursor over it , you ' ll know how many come from your own lands demesne , from your vassals , hired mercenaries , retinues always raised troops and events . After that , go check your target ' s character screen for the same information . If your numbers are smaller than hisher , it ' s probably not a good idea to attack ! Oh , and check money the 3 coins nearby the cap if the target has 150 ish gold , she could hire mercenaries to battle you ! The otehr thing to considerate is how your army is composed . The game has several kinds of troops light infantry , heavy infantry , light cavalry , heavy cavalry , archers , pikemen , horse archers , special troops dependent on culture . Heavy Infantry is generally the best one , so try to have those each county can have at least one castle . Castles have an upgrade called Barracks , which give you more heavy infantry a smaller number of heavy infantry will win against a larger but not so much number of light infantry . Tribal rulers have very few heavy infantry they ' re more usual to Feudal rulers . I don ' t recall how you can see your army composition outside calling them all , joining them to one stack and then hovering the cursor over it to see . Finally , you need commanders people with high Martial attribute 2 crossed swords in their character screen . Use the character finder to find good ones even if they have a red hand , rightclick on then and go to the invite to court option hover the cursor over the white banner to see the modifiers . If the difference between and is 2 or less , you can bribe then with send gift option and then you can invite then . Assign them to your armies and happy fighting ! For more info