Serbia is anointed by God for glory.
The Kingdom of Serbia grew in strength; after a string of defeats against the Byzantine Empire the Serbians took the Byzantine Empire's Cumanian campaign as a time to take back lost land and a time to absorb the Western slavs of Slovenia and Croatia with the Northern Avar pagans. The Kingdom of Bulgaria remained an issue so the Serbs made sure to destabilize Bulgaria. Serbia was at maximum crown authority to squeeze as many soldiers out of its meagre lands. The Bulgarians too sought to increase their crown authority to compensate. This would piss off their vassals who would inevitably form a faction to revolt; lacking in sufficient troops the rebels would have to rely on outside help and so never declined Serbian help. Serbian help would involve ensuring the war lasted as long as possible, killing the Bulgarian loyalists whilst allowing Bulgarian rebels to be slaughtered at regular intervals by angry Bulgarian loyalists. When the next Bulgarian faction King rose to power Serbia would begin prodding the Kingdom of Bulgaria once more, prompting the new King to raise crown authority and renew the cycle yet again. This happened with the Byzantines as well, but as the Byzantines were vastly more stable the Gusars only had a few opportunities to raid the villages of Anatolia for Byzantine soldiers.
Eventually the Serbs acquired all the claimants to the Bulgarian throne it needed to ensure domination. After three wars and heavy resistance Bulgaria fell; swinging from this great victory the Serbs attacked the Byzantines to secure its south sea ports and more wars were to follow. The Byzantines were caught between the Cumanian horsemen and the Serbian horsemen, with the Cumanians eventually converting to Orthodox Christianity to get rid of the Byzantine holy war CB. The Serbs were stopped by the Byzantines at Philippopolis, but by then the Serbs had already made comfortable headway into Byzantine lands in order to establish a buffer for the Eternal Empire.
Old shadows of Bulgarian rule were ever present, however. The Bulgarians attacked with 25,000 men; before the Byzantine War had even officially finished the Serb Gusars with their 15,000 strong army raced towards the river Danube for a confrontation with the Bulgarian host. The Bulgarians had split their army up into three divisions to more rapidly take over the land; this also made them vulnerable to being divided and conquered. Forced into battle the three army divisions attacked the Serbians at Giurgiu Bridge. Unable to bring the full force of their host to bear across the bridge and the rapid waters 15,000 Bulgarians were slaughtered to the tune of only 6,000 Serbs. Some developments north of Turnu in the Bulgarian mountains were of great concern. During the battle of Giurgiu Bridge another host had arose in the mountains, 30,000 strong.
They waited until the battle of Giurgiu bridge had concluded before attacking, no doubt intending to destroy the victor and secure Bulgaria in one devastating blow. The first Bulgarian host safely escaped across the bridge with 12,500 survivors whilst the Serbs prepared themselves for battle, certain with the knowledge that there was nowhere they could run to in time, no retreat left. In hindsight I could have disbanded my levies and saved some of them, leaving my elite Gusars to die, but at this moment I was feeling nothing but the sheer Fun and joy of watching six generations of Miloslav work come crumbling down in a single week.
The 30,000 Bulgarians forded a minor river, harried by the Serbians, yet this was nowhere near enough to stave off defeat. The right flank fell and was slaughtered and then so too did the center fall. As the last hundreds of Gusars of the left flank were facing imminent destruction at the hands of the Bulgarian host something utterly unexpected happened.