Why did St. Ignatius of Antioch write a letter to the Christian church in Rome?

St. Ignatius of Antioch wrote his letter to the church in Rome primarily to urge the Roman Christians not to intervene in his impending execution. As he traveled toward Rome to face martyrdom, he feared that his friends in the city might use their influence to obtain a pardon for him.12

For Ignatius, martyrdom was a profound spiritual goal—a way to imitate Christ’s Passion and achieve perfect union with him. He viewed his death in the Roman arena as the moment he would finally "begin to be a disciple," and he was deeply concerned that any intercession on his behalf would deprive him of this path to perfection. Additionally, in the same letter, he commended to the charity of the Roman church those Syrian Christians who had arrived in the city ahead of him.21