"Be in no doubt, these are better days". These were the words of Arlene Foster as she addressed her DUP colleagues for the first time as leader in 2015.

"Better days than we'd ever have imagined possible or dared to dream about back in the deepest darkest days of the Troubles", she continued.

Six years later, today is a dark day for Arlene Foster herself after resigning her position as party leader and First Minister of Northern Ireland.

The former solicitor has represented her constituency of Fermanagh and South Tyrone as an MLA since 2003.

She became leader of the DUP in 2015, succeeding Peter Robinson and achieved a number of "firsts"; becoming the first female leader of the party, and the first female First Minister of Northern Ireland.

Not long after taking up the role, she celebrated a win for the DUP in the Assembly Elections and securing its place as the largest party in Northern Ireland.

Arlene Foster became DUP leader in 2015

Speaking amid celebrations after the win, she said she was "absolutely delighted" and "it's been a very good day for the party".

But for Arlene Foster and the DUP, there were difficult days ahead.

Her involvement in the Renewable Heat Incentive or "cash for ash" scheme as it became known, led to the collapse of the power sharing government at Stormont in 2017.

A snap election followed shortly after, something that she herself described as "brutal".

The DUP won the election, but only just.

The party beat rival Sinn Féin by just one seat.

The results of the 2017 election also spelled the end of the Unionist majority in Northern Ireland.

Arlene Foster apologised to her party colleagues over her involvement in the RHI scheme at a DUP conference.

An inquiry later cleared her of any wrongdoing.

With the Northern Ireland Executive out of action for three years, Arlene Foster resumed her role as First Minister in January 2020 when power-sharing was restored, with Sinn Féin's Michelle O'Neill in the role of Deputy First Minister.

Arlene Foster and Sinn Féin's Michelle O'Neill

The deal that got them there was entitled "New Decade, New Approach".

But in the year that followed, the agenda has been largely dominated by the Covid-19 pandemic.

Arlene Foster's political career has also been punctuated by battles over Brexit, the backstop and now the Northern Ireland protocol.

She initially said the protocol would give Northern Ireland the best of both worlds, with access to both the UK and the EU single market.

However, she was later forced to take a tougher position on this issue, calling for it to be scrapped.

Following controversy over the attendance of senior Sinn Féin members at the funeral of Bobby Storey last year while Covid-19 restrictions were in place and the subsequent decision of the Public Prosecution Service not to bring charges, Arlene Foster came out against the head of the Police Service of Northern Ireland.

She called for Chief Constable Simon Byrne to resign, in a move that many view as an attempt to appease hard-line members and critics within the DUP.

Six years after she took over, Arlene Foster has become the first DUP leader to be ousted by her own party.