Berlin, Germany (CNN) Despite temperatures far too cold for mid-summer and persistent pouring rain, tens of thousands of Turkish protesters in Cologne were in a frenzy. A sea of red and white flags and signs supporting their president washed over the streets while the crowd burst into song. The chorus has only three words:

"RECEP TAYYIP ERDOGAN! RECEP TAYYIP ERDOGAN!"

Chanting with conviction, the pride etched proudly on their faces, Turks in Germany were displaying their loyalty after the failed coup attempt while also booing German authorities' ban on Erdogan speaking to the gathering via videolink.

The world's largest Turkish diaspora can be found in Germany -- where about three million people with Turkish ethnicity now reside. A third of Germany's Turkish community live in the state of North Rhine-Westphalia (where Cologne is located).

Strained relations

Relations between Germany and Turkey are now almost as stormy as the weather on the day of the protest. Some of the rhetoric coming out of Berlin is sharply critical; many Germans deem Turkey's actions a heavy-handed response in the wake of the military uprising.

The situation got worse on Monday after Turkey summoned Germany's charge d'affaires in Ankara to its Foreign Ministry to express outrage at Erdogan's ban from addressing the anti-coup rally, state-run news agency Anadolu reported.

Many German politicians believe President Erdogan is turning into an increasingly autocratic ruler. One media outlet has even labeled him "The Sultan from the Bosphorus" and lambastes the purges in the aftermath of the failed coup.

Ankara, for its part, believes that Germany is too soft on groups like the PKK -- a Kurdish separatist group that Turkey has been battling for decades. The collective feeling among Turks is that the European Union is essentially leaving Turkey alone in dealing with the refugee crisis. It doesn't help deteriorating ties that EU leaders do not see eye to eye with Turkey when it comes to the bloody civil war in Syria.

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In the past months, Erdogan has launched legal action against a German comedian for writing and then reciting on TV a scathing poem against the Turkish leader. (These lawsuits have since been dropped.) This weekend, Turkish lawmakers accused Germany's constitutional court of infringing upon Turks' rights to free speech in Germany after authorities banned Erdogan from addressing the rally. Turkey's EU Minister and chief negotiator, Omer Celik, said on Twitter that the decision was "against democratic values."

The court made its decision after Cologne police voiced concerns over security. German politicians fired back saying Turkey should worry about its own free speech track record before it criticizes other nations.

The problem with picking sides

In light of the growing strains, many in Germany are pressuring the ethnic Turkish population living here to declare where their loyalties lie -- with Germany or with Turkey?

The answer to that question is not easy. I went to high school only a few blocks from where the pro-Erdogan demonstration in Cologne was held, in Koeln-Deutz. Many of my friends were Turks and identity was never a simple subject for them.

Some of the three million-strong community carry Turkish passports but many more are second or third generation immigrants who were born in Germany and hold German citizenship. But no matter how long ago their families settled here, and even with German citizenship, many struggle to feel accepted by German society as a whole.

Tens of thousands at pro Erdogan demo in Cologne, Germany. #cnn A video posted by Fred Pleitgen (@fpleitgencnn) on Jul 31, 2016 at 7:43am PDT

Integration of the Turkish community has been a problem for decades. There are areas in large cities like Berlin and Cologne where Turkish is the prevalent language. Years ago, I interviewed the headmaster of an elementary school in Berlin-Kreuzberg. She complained that teachers had to rewrite textbooks because children were coming to school with so little knowledge of German that they could not understand instructions because they spoke almost only Turkish at home.

Unemployment among ethnic Turks is high in Germany and many people of Turkish descent complain that employers and authorities discriminate against them in public and professional life. Some feel that Germans expect them to give up their Turkish pride and identity and assimilate into German culture.

Germany: A political battleground

Then came Erdogan . His early years in office turned Turkey from a stagnant and underdeveloped country into a regional economic powerhouse . His success also filled many ethnic Turks with pride and the president, for his part, understood that Germany was a political battleground for his party, the AKP.

"Assimilation is a crime against humanity," Erdogan said at a major rally for his AKP party in 2010, which was also held in the city of Cologne. While many German politicians were outraged by the statements they believed directly called on Turks to reject integration in Germany, many Turks were thrilled and celebrated the man they felt represented a self-confident and proud Turkey.

That loyalty remains until today.

In last year's Turkish parliamentary elections, around 60% of eligible voters in Germany cast their ballot for the AKP, according to Anadolu. And the loyalty also showed last Sunday when 30,000 to 40,000 turned up in the rain to lend support to their leader.

But while many Turks in Germany still grapple with their identity and struggle to answer the question of where their loyalty lies, many of the protesters at the rally in Cologne seemed to have their own answer: They waved both Turkish and German flags. They showed they can love both their ancestral land and their new home in Northern Europe. Perhaps making them a force that could help these two nations overcome their recent quarreling.