Finding strategies to save time is crucial, especially because you don't have much at your disposal.
The Roman Empire doesn't have the punch of the Abbasid Caliphate when it comes to painting the map, but the Defensive Pacts and the Christian limitations in casus belli make it one of the longest, deepest and most satisfying experiences in the game in this writer's opinion.
In some successions, including primogeniture, the second and third in line get a strong claim instead. The difference is that a strong claim can be pressed at any time, while a weak claim can only be pressed in certain situations. A crucial choice you'll have to make is whether or not stay Orthodox. With the infidels out of the way, let's refine our strategy. Provinces are not visible in game, but a message appears when you conquer every single holding in them, as in the case of Italia during the Restoration. Therefore, the magic number is 75%, declare a war whenever your Threat is lower than that.
Wait for your heir to inherit, and then take advantage of a civil war or of a regency (that you may have helped to trigger) to press your weak claim.
Interestingly, going into hiding also results in a regency, so you may manage to press the claim even if an assassination fails.
Jihads can also be triggered by, Switch from middle era clothing and unit graphics to late era. Crusades will unlock in the late 1090s and will be launched soon after. This guide describes how to get the S.P.Q.R. I love Defensive Pacts. According to Steam statistics, the SPQR achievement is held by 0.6% of the players. In Crusader Kings, the old Roman Empire is divided in a number of Provinces of variable sizes.
I didn’t use it much, because it only targets one duchy at a time and is woefully inefficient for taking over large kingdoms. All children of the dying ruler gain a weak claim upon succession, even in elective. Crusader Kings 3, the auspicious heir to Paradox's breakout hit medieval ruler simulator, was announced this past weekend at PDXCon. By now your threat jumps to 100% every time you conquer more than a single county, so better swallow kingdoms whole. Still, I find External to be worth it if vassals focus their energy on outside expansion, saving you more Threat. Extreme prudence, and excellent commanders are key to beat them. If this happens, press your own claimant immediately. It was released on October 14, 2014 alongside patch 2.2. Note that in 2.7.1, the faction will change two laws, which may be more problematic. The holy orders probably have castles near Jerusalem: you can't use the Holdings casus belli against them, which is annoying, but it is possible to revoke the county, grant it to the holy order and then press a de jure claim – if your vassal king doesn't beat you to it.
9/10. You need 20k or 30k men in the target territory, while the bulk of your forces fights enemy stacks or plays whack-a-mole with smaller groups. Who will join these alliances depends on your Threat level, their number of troops and their distance to your nearest border.
Divine Blood (reach a score of 100k), Celebrity (get 15k Prestige), Merchant Prince (get 20k gold) will happen once your empire gets large enough.