Thank you for your input
This is more based on my opinion so I'm sure that I'm repeating what other people have said. Sorry bout that.
The upheavals of 1848 would almost certainly affect them as would the resulting French 2nd Republic and 2nd Empire, both of whom were interested in the idea of France's "Natural Borders" which assumed an annexation of Belgium. Napoleon III might be especially interested given his constant homage to his famous namesake. Europe was hit with two main revolution waves in the 19th century. The first in 1830, and the second in 1848. In OTL, the Netherlands weren't hit with the revolution during 1848, but Belgium was, King William had altered the Dutch constitution to reform the elections and reduce the power that the monarchy held. Something that would need to occur in TTL during 1830, along with other social and political reforms, to give the southerners a greater voice within the assembly. Assuming that Belgium doesn't ever gain it's independence. Massive changes would occur.
Partly correct, the revolutions of 1848 were mainly Liberal, (upper-) middle class who wanted to have a voice. In the United Netherlands it might also happen how ever it might be more socialist and religious as in Protestant low and middle class people who dislike the, by then economic and political, influence.
Let assume William II will be in power for nearly 20 years, there will gradual shift in dominance of power from the North to the South. This shift in power will be evolve due to the fact that William II no doubt will spent most of his time in Brussels instead of the Hague. William II will be not as involved in state affairs as his father was, who ruled on his own, but be more relying on is Ministers. Let assume William II came to power due to the early sudden death of his father, an event clouded in mistery. He might be forced to made several concession or amendment on the constitution in favor of the Liberals.
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One major change would be how Germany would be formed. The most important factor a unified Netherlands would have on the unification process of Germany is Luxemburg. Luxemburg was part of the German confederation and had been garrisoned by thousands of Prussian troops since the Congress of Vienna that ended the Napoleonic Wars. When Napoleon the third tried to buy Luxemburg in 1867, Prussia threatened war. [/QUOTE]
The Luxembourg affair of 1867 will not occur when there is no Belgian revolt. Luxembourg will remain twice as large as it is now. The Luxembourg affair was caused by OTL Willam III and a Dutch secretary of foreign affairs without communication between Cabinet and played out by the Great Powers of France and Prussia.
But it could be a 'casus belli' for a conflict between France and Prussia.
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If we assume equal rights for Walloons which would need to occur for a united Netherlands to prevail, I am certain the people of Luxemburg would want that as well and I don't see anyone objecting, they were relatively satisfied with the Dutch rule. The question is then arises, would Germany or Prussia accept such a act? When Denmark tried to do something similar with Schleswick, it did not, and Prussia was able to incorporate Schleswick and Holstein following a short war. The key to Unification was to have France be isolated in the diplomatic sense, which was achieved through careful diplomacy and Napoleon the third, being very aggressive with his foreign policy.[/QUOTE]
The Walloon will not be a marginalized minority. First during the 19th century French was the language of the upper class in nearly all of Europe. Second a large part of the industrial boom will happen in Walloon.
Further the 2nd Schleswick and Holstein war was mainly caused by completly inresponsible behaviour of certian Danish politicians and handy used by Bismarck.
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On a colonial note this would have a rather large effect, The Congo was only acquired by Leopold of Belgium because of his scheming. He convinced the various European powers that the Congo would be open to traders and missionaries from all countries, and played all of them off of each other. He also convinced missionaries, explorers, and human rights advocates that he would end the slave trade and bring "civilization" to the Congo. It was also used much like a buffer between British and French colonial zones. While this likely would have meant that the Congo as a whole would be heavily divided but the populace and land would have almost certainly been less abused. The lack of a neutral border could have easily created colonial skirmishes that would have soured relations back in Europe. During the Berlin Conference, the Congo region was given to the Belgians as a way to keep the area from becoming a point of contention, if you are to remove that then you would likely see the region carved up between the French, British, and Portuguese. Possibly even given to a "weak" neutral power. (Danish Congo anyone?)[/QUOTE]
The colonization or better, called the increase of influence will be gradual as it was in OTL, but no doubt faster. The Netherlands had overseas possession which need to have economic value. Overseas possessions were not acquired or conquered for prestige while costing a fortune, like France and Germany did in OTL with lots of 'colonies' at the end of the 19th century