At Menstad, where Hydro had warehouses and shipping facilities, the company contended that it had the right to continue shipments from the warehouses using temporary personnel who were not part of the lockout. Strikers considered this strikebreaking and protests resulted.
There was a demonstration on 2 June, and Hydro's management was not satisfied with the efforts of local police. Workers had broken through police lines into the Menstad facility. Temporary workers were brought out into a ring of demonstrators. They had to run the gauntlet through the crowd to get away.
Per Ole Johansen recounts what happened in his book on the Menstad conflict:
"The conflict culminated 8 June with 2,000 workers marching out to Menstad. Several were armed with staffs. Demonstrators chose a negotiating committee to contact the police. They did not, however intend to give in if the police refused to negotiate."
Both sides knew a fight was looming. It wasn't a matter of if, but when. Stones were thrown and the police responded with water hoses and batons. But it was over in five minutes, and the demonstrators beat the policemen who hadn't managed to get away.
The episode was serious and had both legal and political ramifications, as well as attracting a lot of attention. The Farmer's Party government (with Vidkun Quisling as defense minister) sent a large military force to the area, while the conservative press called for a crackdown. The unions refused to cooperate with the police and soldiers.
In the week following 15 June, a number of demonstrators and labor leaders were arrested, and remained in custody until the Menstad conflict was over. There were three court cases; 20 of the accused workers were jailed and fined.
The shipment season came to an end on Friday 19 June, and the contract workers were placed on leave. Hydro managers had feared that new conflicts would break out if they were kept on.
The contract system for dockside work at Menstad ceased at the end of August 1931. Most of the contract workers became employees organized in a union.
The wrapping up of the great lockout of 1931 marked the end of a long and bitter conflict at Menstad.
Per Ole Johansen: Menstadkonflikten 1931. Tiden Norsk Forlag. 1977