The meeting between Prince Orhan and Antonius did not end well.
This is what happens when two men with different ideologies and believes clash with each other. Orhan, who came from a high noble family born and educated under the medieval background which naturally injects him with the pride and responsibilities of a noble, of course he would look down on the commoners who are largely uneducated and uncouth, it is down to his bones, and one cannot blame him for being like this as the craft of chivalry and nobility are widely practised among people in this era, blaming him is just like blaming a cave man living in the pre antiquity era for being unhygienic for not sanitising their food and hands before eating.
While on the other side, we got Antonius who came from a humble background, with no special social status when he was born, and threw himself into becoming a sea man at a relatively young age which eventually became a privateer roaming the seas even before he turned adult. He lived and sailed with people of all backgrounds, higher and lower nobles, gamblers, beggars, town folks, farmers, pirates and soldiers, thus he understands how does a commoner think, feel, react to things, it can be said that he is a normal uneducated pirate who, by luck graced by God, climbed to the position of a Roman noble today.
Thus, there is a fundamental difference between the two of them.
Orhan finally set sail for Anatolia with his mind filled with doubt why is Antonius having such an empathy for the peasants, while Antonius got frustrated and even a little mad at how the Ottoman prince treats his followers like just a mere number, statistics on a paper, a good that can be traded.
Nevertheless, Orhan sailed away, with the support of the Romans, several pashas in Anatolia such as the pasha of Kastamonu, pasha of Hamid, Bey of Karaman, and pasha of Saruhan, the real one of course. He is destined to be pushed into doing something remarkable in Anatolia weakening the Ottoman base of control over here.
Of course, his supporters did not because of a charitable purpose, but with different motives in mind. Constantine hopes to weaken the Ottomans plunge them into chaos so they would be too busy fighting with one another to take a look at Constantinople, while also trying to not dwindle the Ottoman Sultan's control by too much to prevent some ambitious Beys and pashas into leading an army onto Constantinople by only themselves. It is said that Orhan promised Constantine a strip of land along the coast of Kocaeli, including the city of Izmit, or if one is not familiar with this name, the century lost city of Nikomedia, which the name of this place itself is already a strong significance for the Romans.
While for the Bey of Karaman things are pretty simple, he had enough for being a tributary of a Sultan that is only six years old. Seriously speaking, how can a kid be on the throne of a Sultan. He wants to break free from the leash, fly back into the sky and demonstrate that his Beylik can achieve something too.
Lastly for the various pashas and Beys who are vessels of the Ottomans already, they are mostly marginalised from the central sphere of government in the court of Edirne, and with this in mind, they want to use the exiled Ottoman prince as a golden brick to knock open the gate to the Sultan's court for a promotion in ranks, wealth, peasants and land.
Hence, the four various parties, although from different factions, quickly landed on a common ground and made an agreement for collaborative effort to push Orhan onto the throne, with the first step be taking a foot hold in Kocaeli, then slowly expanding his influence into the entire Anatolia, then marching towards Edirne through the Straits of Bosporus with Roman help after handing over the city of Nikomedia.
The War of Ottoman Succession officially began as Orhan Çelebi flew his banners of black horse over the vast mountainous kingdom of Anatolia.
The date is the last day of April, less than a month after Sultan Mehmed's spirit ascended to Jannah.
Wherever Orhan and his men goes, local mayors, rulers and war lords who are already displeased with the rule of the six years old boy and the master behind Candarli Halil Pasha, opened their cities and castles gates welcoming the banners of Orhan, handing over him the keys to the city, tossing the flags of red sky and white crescent and the banner of white horse away, replacing those with the banner of the black horse symbolising they have now jumped overboard to the side of Prince Orhan.
The reason for their changing of side is also plainly simple, they have devoted so much money, time, manpower serving the Sultan Mehmed squandering all the resources raised into the worthless Siege of Constantinople, and now returning without a single copper of loot, but a crime. They must find something to replenish their loses, and if they cannot find it through the walls of Constantinople, they will have to find some where nearby…
By the middle of May, Prince Orhan's forces have snow balled to a staggering size of twenty thousand men, with their gears sponsored by the various lords across the cities he occupied, every day there are even messengers coming to the camps of Orhan proposing to sponsor him with supplies, manpower, logistics support and equipment, just to protect their properties, avoid their newly seeded crops when marching, and do not requisite their men.
Orhan of course, generously agreed to all these terms promising to keep all the cities and towns aside undisturbed as long as they hand over him the keys to the gates of their cities, hang his banner of war, and give their taxes to him instead of the government in Edirne.
It has only been roughly two weeks after Prince Orhan has landed his boots on the shores of Anatolia, and now he already controls a vast territory stretching from Amasra in the North, to Edremit, Adramyttium in the south, and Eskişehir in the East.