Prince Harry arrived at a London court to testify against a tabloid publisher Tuesday, making him the first royal to enter a witness box in centuries.

As part of his mission to rein in the tabloid media, Harry is testifying and being cross-examined over at least two days in his suit against the Daily Mirror.

Prince Harry has entered a courtroom witness box and has sworn to tell the truth in testimony against a tabloid publisher he accuses of phone hacking and other unlawful snooping

Prince Harry testified in London on Tuesday as part of the phone hacking lawsuit he brought against Mirror Group Newspapers, alleging that the tabloid press had hacked his phone and voicemails and those of his friends and associates to illegally obtain information about him.

Prince Harry took the stand in a case against the British tabloid newspaper “Daily Mirror” and more on June 6. He said journalists have “blood on their hands.”

Prince Harry appeared in court to give testimony in his case against Mirror Group Newspapers. On Tuesday morning, the Duke of Sussex arrived at the High Court of the Royal Courts of Justice in London to give evidence supporting his case against Mirror Group Newspapers (MGN).

Prince Harry became the first British royal to testify in more than 130 years when he took the stand in a case against tabloid media outlets. NBC News’ Meagan Fitzgerald reports on the trial as Harry is expected to be back in court tomorrow.