The Duchess of Sussex’s legal action against the Mail on Sunday over its publication of a “private and confidential” letter to her estranged father Thomas Markle has reached the High Court.

But the case is simply the latest chapter in an escalation of hostilities between the British media and the Duke and Duchess of Sussex, who recently announced they are stepping back from their duties as senior royals.

Here is a timeline of key events so far:

– 2016

– July: Harry and Meghan meet in London through friends and become an item.

– October 30: News breaks that Harry is dating star of US legal drama Suits Meghan Markle.

– November 8: Harry attacks the media over its “abuse and harassment” of his girlfriend, with Kensington Palace warning on his behalf: “This is not a game – it is her life.”

– 2017

– October 19: It emerges that Harry has taken the Suits star to meet his grandmother the Queen, whose permission they need to marry.

– November 27: Clarence House announces the engagement. Harry and Meghan pose for pictures at Kensington Palace, and record a television interview. The wedding venue – St George’s Chapel, Windsor Castle – is confirmed the following day.

– December 15: The wedding date is announced as May 19 2018.

– 2018

– May 12: Mr Markle speaks to Harry on the phone, warning him that the story of the staged paparazzi photos, which he was allegedly paid for, was about to break. In one shot, he apparently pretended to read an article about his daughter and Harry online in an internet cafe, while in another he appeared to be being measured for a suit.

– May 14: Mr Markle looks set to miss the wedding amid reports he staged photos for the paparazzi and suffered a heart attack. Meghan appeals for “understanding and respect” for her father. He later issues a public statement through US website TMZ that he had gone to hospital because he had suffered a heart attack.

Mr Markle writes to Meghan saying he is sorry and that he will not be attending the wedding to “spare her any further embarrassment”. On the same day, Harry sends text messages to Mr Markle, urging him to respond to calls and saying that “going public” will only make the situation worse.

– May 15: In a text to her father, Meghan writes: “I’ve been reaching out to you all weekend but you’re not taking any of our calls or replying to any texts.

“Very concerned about your health and safety and have taken every measure to protect you but not sure what more we can do if you don’t respond.”

– May 17: Meghan confirms her father will not be attending her wedding, saying he needs to focus on his health.

– May 19: Harry and Meghan marry at St George’s Chapel, Windsor Castle, and become the Duke and Duchess of Sussex.

– August: The duchess writes a letter to her father, reportedly accusing him of breaking her heart “into a million pieces” by giving interviews to the press.

– October 15: The duke and duchess are “very pleased” that Meghan is expecting a baby in the spring of 2019, Kensington Palace announces.

– November 25: Mr Markle texts the duchess saying: “I want to reach out to you or try to reach out to you one more time.

“You apparently have just written me off and now it’s telling me I guess for the rest of my life?”

Meghan will later claim in court documents that she never received this text message.

– 2019

– February 10: The Mail on Sunday publishes an article with the headline “Revealed: The letter showing true tragedy of Meghan’s rift with a father she says has ‘broken her heart into a million pieces’”. An article is also published on MailOnline.

– May 6: Archie Harrison Mountbatten-Windsor is born at the Portland Hospital in London after Meghan goes into labour in the early hours of the morning.

– May 8: The duke and duchess present baby Archie to the world at a press briefing at St George’s Hall at Windsor Castle.

– August: The couple are heavily criticised in the press for using private jets to go on holiday with Archie to the south of France. In September, Harry defends the use of the transport and claims it was to “ensure their safety”.

– September 23: Harry and Meghan take Archie on a two-week royal tour of South Africa, while the duke also visits Botswana, Malawi and Angola alone.

– October 1: Prince Harry issues a strongly worded statement criticising the press for its coverage of his wife. At the same time, the Sussexes release a statement confirming they will take legal action against Associated Newspapers, publisher of the Mail on Sunday, for the “intrusive and unlawful” publication of one of her private letters.

– October 4: A royal source confirms the Duke of Sussex has started legal proceedings against the publishers of the Sun and the Daily Mirror newspapers over alleged phone hacking.

– October 5: Thomas Markle claims that he did not intend to share a private letter sent by Meghan, but felt pressured to do so after he was “mischaracterised” by an article in People magazine.

– October 11: Meghan’s particulars of claim are filed at the High Court, alleging the Mail on Sunday published “a private and confidential letter to her father, Thomas Markle, which detailed her intimate thoughts and feelings about her father’s health and her relationship with him at that time”.

– October 21: Meghan reveals her struggles with royal life in an ITV documentary filmed during the duke and duchess’s trip to Africa, and says: “It’s not enough to just survive something… You’ve got to thrive.” In the same programme, Harry reveals he and brother William are on “different paths”.

– November 14: The duke and duchess confirm they will not spend Christmas at Sandringham with the royal family. It is later announced they are taking a six-week break and they spend the holidays in Canada.

– 2020

– January 8: The duke and duchess announce in a statement released by Buckingham Palace they are stepping back as “senior” members of the royal family and are “working to become financially independent”. They also reveal they will split their time between the UK and North America.

– January 14: Associated Newspapers files its defence, claiming the Duchess of Sussex was more worried about the “unflattering” effect of the publication of letter extracts written to her estranged father than any breach of her data protection rights. The defence document also reveals that the publisher will rely on evidence from Mr Markle, meaning that should the case go to trial both Meghan and her father may have to testify against one another.

– January 19: The Duke of Sussex describes the media as a “powerful force” during a speech at a private event for his charity Sentebale in which he referred to the impact of overwhelming media intrusion on the daily life of his mother Diana, Princess of Wales, who was killed in a crash after her car, driven at speed by a drunk chauffeur, was chased through the streets of Paris by the paparazzi.

– January 27: Thomas Markle is interviewed on ITV’s Good Morning Britain and asks the Duke of Sussex to “man up” and meet him. He describes the breakdown of his relationship with Meghan as “ridiculous”, and calls for a reunion. On the same day, he says he is willing to testify against his daughter, telling The Sun: “I’ll see Meghan in court.”

– April 20: Details of calls and texts by the duke and duchess to Mr Markle in the days before their May 2018 wedding are revealed in court documents. In their reply to the Mail on Sunday’s defence, the duchess’s lawyers say she first discovered her father was in hospital through his statement to US website TMZ.

On the same day, the duke and duchess announced they have severed all dealings with Britain’s tabloid press, writing in a strongly worded letter to the editors of The Sun, Daily Mirror, Daily Mail and Daily Express that they will not “offer themselves up as currency for an economy of clickbait and distortion”.

– April 24: First High Court hearing in Meghan’s legal action against Associated Newspapers. Mr Justice Warby hears an application by the publisher to strike out parts of Meghan’s claim. The duke and duchess are understood to listen in to the part of the hearing conducted by her lawyers. The case is heard remotely as a result of the Covid-19 pandemic.

– May 1: Associated Newspapers wins the first High Court skirmish in the legal action. In a ruling, Mr Justice Warby strikes out parts of Meghan’s claim against the publisher, including allegations that it acted “dishonestly” by leaving out certain passages of the letter. The judge also struck out allegations that the publisher deliberately “stirred up” issues between Meghan and her father, and that it had an “agenda” of publishing intrusive or offensive stories about her.

The judge said those allegations should not form part of her case at this stage, because they were “irrelevant” to her claim for misuse of private information, copyright infringement and breach of the Data Protection Act. But he also said those parts of her case may be revived at a later stage, if they are put on a proper legal basis.

– July 1: Meghan applies to the High Court to stop Associated Newspapers from naming her five friends who spoke anonymously to People, a US magazine, to defend her from tabloid “bullying”.

– July 29: Meghan’s claim returns to the High Court for another preliminary hearing. Mr Justice Warby hears two matters – one on costs and an application to prevent Associated Newspapers from disclosing the names of the five people who spoke anonymously to People magazine.