Whilst i do not know anything about Joseph, I do know about Napoleon’s other brother, Louis, who was appointed as King of the Netherlands. So I will try and answer your question through his rule.

Though he did rise quickly in his military career due to his big brother and fought battles with and for Napoleon, the relation between the two brothers was never good. Louis resented being overshadowed by his brother and did not like having to subject himself to Napoleon. Napoleon forced Louis to marry his stepdaughter Hortense, as he could not have children himself so he obligated Louis with the continuation of the Bonaparte bloodline. The couple was a spectacular mismatch and Louis lamented marrying her in his memoires. He even suspected her to be a spy for his brother and the couple spent decades in separation, whilst Hortense kept his children from him. He also did not want to be King of the Netherlands, as the cold and wet weather would be bad for his rheumatism. Eventually he was also forced into this by his brother and moved to the Netherlands in 1806.

When he arrived, the Netherlands had been through a rather tumultuous decade. Though having been a republic for two centuries, the country had been mostly ruled by one family: the Oranges. Tensions had risen between the ‘Orangisten’ (on the side of the Orange family), and patriots who wanted more influence of the common people. In 1793 the Republic entered into war with France, which ended in 1795 when the French invaded and declared the Batavian Republic, led by a dutch government but a vassal of France. A lot of radical changes were implemented: the first constitution was written (cynically called the ‘fat book’ by the dutch), a human rights declaration was written, and driving was switched from left to right. This constitution formed the basis for the current dutch constitution and declared among other things, all citizens equal under the law (no more religious repression); strict separation of state and church; and centralization of the government which took away much of the autonomy of the provinces. In the following years there were multiple coups and multiple new constitutions written, all with the support (but never to the satisfaction) of Napoleon, so in 1806 he decided that the Netherlands would be a kingdom and his brother the king.

Despite suddenly being a monarchy after two centuries of being a proud republic, the arrival of Louis was surprisingly met without any notable resistance. Though the country could roughly be divided in three groups - the Orangisten who wanted the Orange family back, patriots who wanted the Batavian Republic back, and moderates who resigned to the new situation - the dutch were tired after a decade of revolts and almost immediately settled in their new form of government.

Though originally not wanting to become King of the Netherlands, upon arrival Louis was incredibly ambitious and dreamed of becoming the embodiment of the nation. Not just for himself, to finally be independent from his brother, but he also genuinely wanted what was best for the country. This was not what Napoleon wanted; he warned Louis that he may be King of the Netherlands, but he was French above all. Louis implemented changes to the country which last to this day: he changed the capital from The Hague to Amsterdam; established the Royal Library, the Society of Academic Science and Rijksmuseum; introduced the first universal map of the Netherlands and a uniform currency; implemented obligatory public education accessible for all classes (which later by inspectors was deemed the best system of Europe); and started a national registry which some poor dutch people still suffer from today, as not everyone was pleased to be forced to choose a surname, so the dutch phonebook is filled with a wide range of idiotic surnames like ‘Naaktgeboren’ (Nakedborn), ‘Spring-in-’t-veld (Jump-in-the-field), and some downright vulgar names (which I will not translate here). The most ironic, and iconic, change he made in regards to language: in the country a multitude of dialects were spoken and the elite spoke french. Louis really tried, but never really mastered the dutch language. Despite his life being unquestionably easier if he would have ruled in french, he made dutch the official language of the country. So the government and elite, which had long ruled the country by speaking french, only started speaking and ruling in dutch by a decree from a French king.

Louis also made a considerable effort to actually get to know his country. He toured around, and spent quite some effort in often overseen (not just historically but also in current day) provinces like Drenthe. In his reign he had to deal with some disasters: in 1807 in the centre of Leiden a ship carrying 359 barrels of gunpowder exploded, killing 160, wounding 2000 and destroying 200 buildings. Louis arrived in the city on the same evening and immediately took charge. Besides giving orders, he also physically helped out and saved at least one child. After a flood in 1809 in the Betuwe, Louis spent two days in the area and again helped physically by filling bags with sand. After this he was nicknamed ‘The Good’ and ‘Father of the Unlucky’ by the dutch and his popularity was soaring.

He was not, however, very popular in France. Though in name the Netherlands was an independent country, in hierarchy an emperor stands above a king and Louis was a vassal to his brother. Napoleon did not care about the Netherlands, and just wanted the dutch to pay him taxes. He wrote plenty of chastising letters to Louis. Napoleon had implemented a ‘Continental System’, which was met by bitter resistance from Louis. He refused drafting dutch men for the French army, in theory went along with Napoleon’s trade ban against the English but in reality never reinforced this rule, resisted the imposed taxes as much as possible, and fired his french political counsel which he suspected to be spies to replace them with dutch politicians. This caused him the wrath of Napoleon, and in letters between the two brothers, Napoleon becomes angrier and angrier. Louis grows more desperate with each letter, pleading not to bankrupt the country and even opening letters writing that he knows that whatever he does will be disapproved of by Napoleon. Napoleon eventually broke off correspondence, a very public and humiliating break for Louis. After four years, Napoleon was fed up with his brother and forced him out of the Netherlands and annexed the country into his empire. Louis, who had seen this coming, abdicated a week before and left a letter to the dutch people, writing that he never seen a people so good and virtuous. He left for France without any notice or ceremony, his departure being as quiet and unnoticed as his arrival.

Louis did some weak attempts to regain the throne of the Netherlands, but never succeeded. After Napoleon was defeated in 1815, Louis published some scathing letters about his brother, breaking the family bond forever. He spent the rest of his years in exile in Florence.

His legacy is as tragic as his life, as the dutch decided to stay a Kingdom and welcomed back the Orange family, who are still the ruling monarchy today. This makes for the remarkable fact that the Netherlands is both one of the first republics, and one of the last standing monarchies in the world. In a country with a 500 year history of being ruled by an Orange, the fact that the first king was a French man is seen as painful. Therefore, there has not been much attention to Louis. In schools, his reign usually is an afterthought between the Batavian Republic and William I. There are no statues for him or dates named after him. The legacy of his short reign however, has shaped and changed the country to this day.

This is a really good documentary about his life and his reign. It is in dutch, but has english subtitles.