Several thousand pro-Kurdish protesters marched through streets of the German city of Cologne on Saturday to demonstrate against Turkey's military intervention in the Syrian Kurdish enclave of Afrin.

The largely peaceful protest saw a nearly 1-kilometer (0.6-mile) line of Kurds and anti-war activists snake through the city waving flags and shouting slogans against Turkish President Recep Tayyip Erdogan and in support of the Kurdish People's Protection Units (YPG) in Afrin.

"Child murderer, woman murderer, terrorist Erdogan," protesters shouted. "Long live the resistance of Kurdistan" and "Long live the YPG" were other slogans, yelled out as Kurdish music praising guerrilla fighters blared from the back of an old truck.

About 2,000 police were deployed for the protest, which drew at least 20,000 demonstrators.

Read more: Turkey's military offensive against Kurdish-held Afrin: What you need to know

Banned flags

Halfway along the planned march route, riot police backed by water cannon tanks blocked roads leading to Cologne's iconic cathedral after hundreds of flags were unfurled depicting Abdullah Ocalan, the imprisoned leader of the outlawed Kurdistan Workers' Party (PKK).

Police corralled protesters and ordered Ocalan and PKK flags to be dropped — a demand that was met with slogans praising the PKK and Ocalan.  Eventually police ordered the protesters to disperse, which most did peacefully near the planned end of the protest.

Read more: Who are the Kurds?

A Cologne police spokesperson said two people were detained for handing out stocks of Ocalan flags and that many others would be given fines for waving PKK-related flags.

Last March, Germany's Interior Ministry issued new rules, banning overt symbols of the PKK and Ocalan, as well as affiliated organizations. The new policy also prohibits Syrian Kurdish flags — including those of the YPG.

The ban has been a major issue for German-Kurds, many of whom consider Ocalan their leader and sympathize with the PKK. The ban on symbols of the YPG and its allied Democratic Union Party is considered particularly insulting by Kurds as it is under that flag that the Syrian Kurds defeated the Islamic State (IS) in their region.

To reduce the possibility of clashes — and because the YPG flag was related to the anti-war protest — German authorities allowed it this time.

'We are not terrorists'

The large mobilization in Cologne caps a week of dozens of smaller daily protests in Germany against Turkey's offensive in Afrin organized by NAV-DEM, an umbrella organization of Kurdish associations.

Germany's domestic intelligence agency reports that NAV-DEM is close to the PKK, which is "the biggest and most powerful foreign extremist organization in Germany."

For six years, Afrin has been controlled by the YPG, a Kurdish militia that is affiliated with the PKK. The militia is the main component of the US-backed Syrian Democratic Forces, a main faction in the fight against the IS.

The YPG, and hence the PKK, have become the flag bearers of the Kurdish nationalist cause by saving many members of the Yazidi ethnic group from genocide at the hands of IS in Iraq, defeating IS in the heroic battle of Kobane and then pressing a US-backed offensive to crush IS in Syria. Meanwhile, they have set up self-governing areas in Afrin and northeastern Syria that have inspired Kurds in the region and diaspora.

"For the PKK in particular, the past couple of years have been a useful period to rekindle interest and mobilize people in the diaspora around the glorious narrative of victimhood and martyrdom," said Alexander Clarkson, a lecturer for German and European Studies at King's College London who specializes in diaspora communities in Germany. 

Turkey's assault on Afrin appears to have been green-lit by Russia, and the United States has not helped its Kurdish proxies in their fight against a NATO ally. The EU has also been fairly quiet.

"What Afrin does as a next step is that it adds the narrative of betrayal," Clarkson said, adding that this can be used to mobilize the Kurdish diaspora around the idea that the PKK/YPG is the only protector of the Kurdish people.

"We want people to know we are not terrorists," Agit, a Turkish Kurd born in Germany, said at Saturday's rally. "The YPG fought IS to defend Europe and the Kurds, and now Turkey is attacking them."

Jamil, a Syrian Kurd who fled Aleppo to Afrin before coming to Germany via the Balkans three years ago, said the YPG had only protected people in the region, which over the course of the civil war has largely been surrounded and besieged by jihadi fighters, Turkey and Turkish-backed rebels.

"Turkish warplanes are dropping bombs on villages, women and children, but the YPG never attacked Turkey from there," he said, taking out his phone to show a Facebook feed filled with video after video of destruction brought on during the offensive in Afrin.

Weapons sales

Kurdish organizations in Germany are trying to mobilize public opinion and allies on the left around an issue that has always been sensitive and a political hot button: weapons sales.

German weapons, including Leopard tanks, are being used by the Turkish army in the Afrin operation. The offensive comes as the German government considers further weapons and tank deals.

"German tanks out of Kurdistan, out of Afrin" has been a common slogan at protests across Germany over the past week. It is one that may resonate with many Germans.

In a telephone interview ahead of Saturday's protest, Ayten Kaplan, the co-chair of NAV-DEM, listed grievances ranging from the arms sales to Turkey to German Foreign Minister Sigmar Gabriel's saying Ankara had a right to defend itself — even though the YPG did not attack Turkey before the Afrin operation.

A former parliamentary candidate for Germany's Left party, Kaplan accused the government of being soft on Erdogan's "fascism," but said the German and international public were sympathetic to the Kurdish cause.