Even if concrete, immediate concessions were unlikely to emerge, though not for lack of trying by the farmers.

Jean-Francois Ricker, a farmer from southern Belgium, braved the winter night close to E.U. headquarters and said he expected 1,000 to 1,400 vehicles. “There will be a lot of people. … We are going to show that we do not agree and that it is enough, but our aim is not to demolish everything.”

Most of the protesters have been young farmers supporting families, who feel ever-more squeezed by higher energy prices, cheaper foreign competition that does not have to abide by strict E.U. rules, inflation, and climate change that either withered, flooded or burned crops.

Similar protests have been held across the E.U. for most of the week. Farmers blocked more traffic arteries across Belgium, France and Italy on Wednesday, as they sought to disrupt trade at major ports and other economic lifelines.