 Complete the following phrase:  On 15 September, Białystok was occupied by the Lötzen Fortress Brigade under the command of General Otto-Ernst Ottenbacher. Two days later, on 17 September Soviet troops joined them. Between 20 and 22 September discussions were held at the Branicki Palace regarding the transfer of the city from German to Soviet hands. According to the agreement, the Wehrmacht was to leave the city until 22 September by 14:00. At the conclusion of the negotiations, the delegations went to a dinner in Ritz Hotel. And so, On 22 September a ceremony of handing over the city was held at the courtyard of the Branicki Palace with the participation of Ivan Boldin who was the commander of the Cavalry-Mechanized Group in the Belarusian Military District and Andrey Yeremenko who was the commander of the 6th Cavalry Corps. The Germans handed over power to the Soviets and withdrew. The city passed to the Soviet Union with respect to the secret protocol of the 