Acts 16:19–40 provides a clear picture of what had happened in Philippi, where Paul and Silas were beaten publicly and thrown into prison, even though they had not legally been found guilty of the accusations made against them. Such treatment would have caused offence to anyone, but was doubly offensive in this case because Roman law did not allow Roman citizens to be treated this way, and Paul and Silas were Roman citizens (Acts 16:37).
2 But though we had already suffered and been shamefully treated at Philippi, as you know, we had boldness in our God to declare to you the gospel of God in the midst of much conflict.