It was a sorry throwback to the shameful spectre of football’s hooligan days of the 1980s.
Violent yobs, drunken fans and a night of shame at the Emirates as 20,000 Cologne supporters went on the rampage.
What started out as merry travelling fans completely overwhelmed proceedings and led to genuine security and safety fears which could - and arguably should - have seen the game called off.
It was completely out of control outside the Emirates as Cologne fans tried to storm the turnstile gates, attacked stewards and burst through police cordons outside.
Arsenal and Cologne will now face a full scale UEFA investigation with possible sanctions including heavy fines and potential ground closures in the future.
The Cologne fans are known for being some of the most passionate in the Bundesliga and they were determined to make a party of their first European game in 25 years.
More than 20,000 fans applied for tickets and yet there was only 3,000 available in the away end so the rest still travelled to London anyway.
But what was supposed to be a party quickly turned nasty as the scenes outside of the stadium escalated alarmingly.
Thousands of Cologne fans marched through central London at lunchtime, boozing their way through Soho and towards North London.
They then descended on Islington and they arrived so early and in such great numbers that it appeared to catch out police and security.
While there were 110 police officers on duty for the game and extra stewards, by the time they took up positions the Cologne fans were already there. They drafted in more police but control had already been lost.
Trouble quickly kicked off with fighting and scuffles on the bridges which led to the stadium from both Drayton Park and near Arsenal Underground station.
Cologne fans were in their thousands outside drinking heavily and began to try and storm their way into the ground. It was more trouble between Cologne fans and the police trying to get in without tickets rather than clashes between rival supporters.
Arsenal put the stadium under lockdown and at 7pm the place was deserted inside apart from a couple of hundred away fans who had obviously forced their way in.
The worry at that stage was whether to let fans in amid fears of the number of Cologne fans in the home sections.
When they finally let fans in the ground by about 7.45pm, the Cologne fans in home sections caused fights as they tried to force their way stewards to get into the away end.
The Cologne fans in the away end began chanting and bouncing up and down - only for huge swathes of German supporters around the rest of the ground to join in. The segregation has been lost and fans were completely out of control.
But, finally, Arsenal decided that calling the game off was more of a risk than going ahead as they would have to get everyone out and then try to play it all over again.
It was a very bad night for European football and a very unhappy first night in the Europa League for Arsenal.
