The Warsaw demonstration was organised by far-right groups as Poles celebrated their country's Independence Day, with the turn-out dwarfing that of previous years.
It attracted far-right and nationalist campaigners from elsewhere in Europe, including the UK’s Tommy Robinson, alongside protesters from Sweden, Germany and Slovakia.
The march was one of many events marking Poland's rebirth as a nation in 1918 after being wiped off the map for 123 years. Polish Independence Day marks the country regaining its sovereignty at the end of World War I after being partitioned and ruled since the late 18th century by Russia, Prussia and the Austro-hungarian Empire.
Earlier in the day, President Andrzej Duda attended several official ceremonies alongside European Union President Donald Tusk, a former Polish prime minister.
Poland has seen a surge in nationalist thinking and activity since the collapse of communism, following years of living behind the iron curtain. The country is believed to have the fifth highest number of far-right activists in the world, behind Germany, Hungary, the Czech Republic and the United States.
In the 2015 election, anti-EU populist nationalist party the League of Polish Families performed well, seemingly emboldening those with far-right leanings.
The march and the accompanying media attention has overshadowed the official state observances and other patriotic events.
Some participants expressed sympathy for xenophobic or white supremacist ideas, with one banner reading: “White Europe of brotherly nations.”
One participant interviewed on state television station TVP said he was taking part “to remove Jewry from power.”
Participants marched under the slogan “We Want God”, words from an old Polish religious song that the US President, Donald Trump, quoted during a visit to Warsaw earlier this year.
Speakers talked of standing up against liberals and defending "traditional" Polish Christian values.
The organisers included the National-Radical Camp, the National Movement and the All Polish Youth, radical organisations that trace their roots to anti-Semitic groups active before World War II.
Many carried the national white and red flag while others set off flares and firecrackers, filling the air with red smoke. Some also carried banners depicting a falanga, a far-right symbol dating to the 1930s.
While the conservative ruling party was not involved in the march, TVP, the state broadcaster, called the event a “great march of patriots".
A smaller counter-protest by an anti-fascist movement also took place, while police and organisers kept the two groups apart to avoid the possibility of violent clashes.
Rafal Pankowski, head of the anti-extremist association Never Again, says that despite the references to God, the march should not be viewed as being inspired by religious beliefs.
“We know that Donald Trump is not the most religious man, and I think that most of the organisers are not very religious, either,” Mr Pankowski, a sociologist, said.
“But they use Christianity as a kind of identity marker, which is mostly about being anti-Islam now.”
Associated Press contributed to this report
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