 Complete the following phrase:  The arrest came about in the context of a wave of strikes across the country, triggered by intensifying economic hardship. Iwan Katz delivered a speech in Hannover which was believed by the authorities to have caused or contributed to serious street disturbances. It is not clear how long he was detained. More serious and sustained street disturbances erupted in Hamburg a couple of months later, over three days towards the end of October 1923. The so-called 