Kate Middleton and Prince Harry stepped out for a rare joint appearance earlier today at Westminster Abbey. Despite rumors of a rift between them, Prince William's wife and younger brother appeared to get along well. But why did they sit apart during the service?

While Middleton usually takes precedence at Westminster Abbey, the Duchess of Cambridge attended the Anzac Day Service of Commemoration and Thanksgiving without her husband, Prince William, on Thursday, so she had to sit at a spot furthest from the altar, as shown in photos released by the palace.

This time, Prince Harry, who is sixth-in-line to the throne, was prioritized and given the seat closest to the altar because royals by blood take precedence over those who marry into the royal family, according to Hello! magazine. The Duke of Sussex sat next to the Duke of Gloucester, Queen Elizabeth II's paternal cousin, during the service.

But while they may not have sat together during the service, Middleton and her brother-in-law did enter Westminster Abbey together.

Usually, there is an order as to how royals enter venues, with the most senior members of the royal family arriving last. In the case of Prince William and Prince Harry, Prince Charles' older son and Duchess Kate would enter after the Duke and Duchess of Sussex.

However, this royal protocol is only really followed when Queen Elizabeth II is present, so this time, Prince Harry accompanied Middleton, whose husband is currently on an official visit to New Zealand.

Prince William, Kate Middleton and Prince Harry
Prince William, Kate Middleton, and Prince Harry during The Patron's Lunch celebrations for The Queen's 90th birthday at The Mall on June 12, 2016, in London. Getty Images/Jeff Spicer

Meanwhile, there was a possibility that Middleton could have attended the service alone as Prince Harry's name was not been printed in the program. While Prince Harry had been planning on joining the congregation, his name was not been included as his wife, Meghan Markle, is nearing her due date and could give birth to their firstborn anytime.

Anzac Day is held in honor of the Australian and New Zealand Army Corps who died during the 1916 Gallipoli landings, along with the men and women who risked their lives during wars.

While he wasn't able to join his wife and brother, Prince William still made sure to mark Anzac Day over at New Zealand by attending a service. The second-in-line to the throne is on a two-day visit to the country on behalf of Queen Elizabeth II to pay tribute to the victims of the horrific Christchurch mosques terrorist attack.