On February 22, 2019, sudden and unprecedented protests swept Algeria. A year on, despite bringing down a president, the "Hirak" protest movement faces mounting challenges.

Massive anti-government protests held every Friday quickly gathered momentum: six weeks in, president Abdelaziz Bouteflika resigned after 20 years in power.

But Algeria's military was quick to reassert control and by the time presidential elections were held in December, a former Bouteflika ally succeeded him in a vote deeply opposed by protesters and shunned by most voters.

"With the presidential election, we passed into act two, with all the spectre of improbability, uncertainty and instability" that entails, Karima Direche, an historian of contemporary North Africa, told AFP.

"It matches what Algerians have been saying for a year: 'Everything is moving and nothing is changing.'"

While a year of weekly protests has not yet brought down "the system" that they challenged, the Hirak movement has profoundly changed Algeria's political landscape.

Bouteflika's resignation and the imprisonment of corrupt businessmen and politicians are "tangible results, even if the main demand of regime change and systemic reform is far from having been achieved", said Dalia Ghanem, a researcher with the Carnegie Middle East Center in Beirut.

But Hirak's biggest success, she said, was "the increased awareness of Algerians and their desire to reconnect with politics... without fear of another civil war".

A brutal war between the Algerian army and Islamist rebels killed some 200,000 people in the 1990s.

The trauma of the conflict was exploited under Bouteflika to discourage dissent, and until February 22 had rendered large protests on the streets unimaginable.

Ahead of the first protests, Algeria's political system had remained focused on presidential polls that were widely expected to return Bouteflika to power -- despite the 82-year-old being largely incapacitated since a stroke in 2013.

Cut off from the public, the regime sensed growing anger but underestimated it.

Young Algerians -- disproportionately affected by massive unemployment in a country where the majority is under 30 -- were fed up with being represented by a wheelchair-bound octogenarian whose rare public appearances elicited mockery online.

Simmering anger peaked when, during a meeting of the president's party, a portrait of Bouteflika was addressed by party apparatchiks in the absence of the ailing leader.

Calls to protest on February 22 began multiplying across social media.

Few expected the movement to take hold though, especially in Algiers, where since 2001 public rallies had been banned.

But then on the first Friday, overwhelmed police stood aside as tens of thousands of peaceful demonstrators poured out onto the streets.