In April 1646 after meeting with Cossack officers (starshyna), Władysław IV Vasa secretly chartered them for rallying to the Cossack army for the upcoming sea campaign against the Crimean Khanate, increased the size of the Zaporozhian Host to 12,000 and gave them 6000 talers to equip "sixty well-armed boats". The king gave his letter to the Military Yesaul Ivan Barabash. who headed the Cossack Diplomatic Mission to the royal court., Among other Cossack officers was Bohdan Khmelnytsky, who at that time was a company commander of Registered Cossacks Chyhyryn Regiment. Other members included another Yesaul, Ilyash Karaimovychm and regimental Yesaul Ivan Nestorenko.