From Round 11:
Sisiutil said:
Shortly after this, Mehmed declared war on Ragnar.
...
By now he was at war with both Darius and Mehmed, so I had to bribe them both to keep Ragnar from becoming their vassal.
Hahaha, so much for:
Ragnar is only a candidate for a Pass 3 Total War (which seems to be the least likely war in civ, if the AIs don't have too high costs for units).
CIV and its random numbers...
As to Hannibal's huge drop in power:
IMHO it is very unlikely that this is the result of his Ex-Vassal Pacal breaking free from him. Pacal voluntarily became Mehmed's vassal shortly after and there is no comparable increase in Mehmed's power.
So instead I suspect it is due to Hannibal's true commitment to go for Culture with a

-slider >=80% or something! With no beakers per turn and low taxes he will enter financial-trouble-mode (Inflated Costs > 60% of beakers + taxes income; >68% when aiming for cultural victory). The following evil "while-loop" in CvPlayerAI::AI_doMilitary() seems to let him disband all excess units that have <2XP until he is not in financial trouble anymore or has a UnitCost of zero.
Code:
[SIZE="3"]while (AI_isFinancialTrouble() && (calculateUnitCost() > 0))
{
if (!AI_disbandUnit(1, false))
{
break;
}
}[/SIZE]
You seem to avoid Coal Plants. If this is because you are intimidated by the threat of Global Warming, please read further down in the thread bjam posted. Coal Plants and unhealthiness from power have absolutely no effect on Global Warming!
But the most interesting thing about the current save is, Mehmed has is hands full!
This means that he decided to consider starting a war and found a valid victim during the following checks (AI_doWar). He is currently pleased with you and Justinian, cautious with Hannibal (+Izzy) and furious with Darius who is therefor also his worst enemy. It appears he is heading for him, he hates Darius, has a higher power than him and has declared on him before.
But wait, this table shows whether a victim is a valid target for the respective wars or the reason why not.
Darius is (just as described for Ragnar above) only a valid target for a Pass3-TotalWar and even this is rather uncertain, because Mehmed is afraid of distant enemies (he has a MaxWarDistantPowerRatio of only 50). So in Pass3 he checks whether the victim's power is lower than his defensive power (his own + power of vassal Pacal) multiplied by 1.5 * MaxWarDistantPowerRatio/100.
Short (P_Darius < 0.75*(P_Mehmed+P_Pacal)) ? WAR : PEACE.
All of this will only be tested for the case that he considers a TotalWar and doesn't find a valid victim in Pass1 and Pass2. So what about Hannibal? WAAAAARRRRR!!! (Hanni is not liked enough, weak enough, a valid LandTarget and shares a long enough border with Mehmed to become the only possible Pass1 victim and will therefore be DoWed.)