Quoting Steve Cushion in On Strike Against the Nazis, pages 11–2:

On 11 February 1941, about fifty WA [Weerbaarheidsafdeling, a fascist paramilitary] members marched through Amsterdam to Waterlooplein, a neighbourhood where many Jews lived, putting up signs saying ‘No Jews Allowed’ as well as vandalising the old Jewish quarter. In response, Dutch opponents of the occupation, both Jews and others, created knokploegen, self‐defence groups that became involved in violent confrontations with the WA.

In one of these fights, WA member Hendrik Koot was wounded and died a few days later. In response, the [Axis authorities] temporarily closed off the Jewish quarter. On 19 February, a massive fight broke out in the Jewish ice‐cream parlour Koko after the police tried to enter but were confronted with a knokploegen self‐defence unit from the neighbourhood, injuring several officers[.]

The [Axis authorities] used the incidents as an excuse for the first round‐ups of Jews. On 22 and 23 February 1941, 425 young Jewish men were rounded up, beaten and taken away. To resist this growing [Axis] repression the Communist Party of the Netherlands (CPN) held an open air meeting at the Noordermarkt. There, they discussed how to stop the persecution of the Jews and the institution of forced labour.

The 250 people present decided to call a strike. On Tuesday 25 February, the tram workers went on strike, while dockers and shipyard workers walked out in Amsterdam Noord and marched across the river. The strike spread to other trades and the strikers marched through the streets, calling on people to join in.¹²

Journalist Salomon de Vries wrote in his diary:

The news ran round through the city. The Amsterdam Dry‐dock Company, the shipbuilding industry, Vries Lenz, Fokker — they’re on strike everywhere! The ferryboats aren’t running! The trams aren’t running!

Mientje Meijer worked in a clothing factory. Her husband was one of the organisers of the tram strike.

I kept walking to the window. Finally I saw him, and he nodded. I could feel my heart freeze. I looked into the shop and saw all those girls and the boss. I wasn’t at all accustomed to speaking before a group. I said, “Ladies, all of Amsterdam has come to a standstill because they’ve been rounding up Jews and taking them away. We’ve got to join in”. To my surprise everyone took to the streets. I thought, “now I’m going to be sacked”, but even the boss went along! We went to the Noordermarkt and the procession just kept growing. It was overwhelming.¹³

Over 300,000 workers in Amsterdam and Utrecht went on strike that day and the next in what was effectively a regional general strike. The [Axis] quickly responded with great ferocity, opening fire and throwing hand grenades, killing nine and wounding about thirty‐five other demonstrators. The mayor was forced to resign and many city workers were sacked. Many Communists were arrested, some deported to Buchenwald and a handful executed.¹⁴

But news of this action quickly spread to neighbouring Belgium.

(Emphasis added.)