Treaty of London (1867)

The Treaty of London (1867), also known as the Second Treaty of London, was a multilateral treaty signed on May 11, 1867, concerning the neutrality of Luxembourg. It aimed to resolve the Luxembourg Crisis of 1867, a diplomatic clash between France and Prussia over who would control the Grand Duchy of Luxembourg.

The treaty reaffirmed Luxembourg's independence and neutrality under the collective guarantee of the Great Powers: Austria, Great Britain, France, Prussia, and Russia (Italy later acceded). The fortress of Luxembourg, a major point of contention, was to be dismantled, and the Prussian garrison stationed there was to be withdrawn. The Grand Duchy was declared perpetually neutral, meaning it could not enter into military alliances or allow foreign troops to be stationed on its territory.

The treaty effectively prevented Luxembourg from being annexed by either France or Prussia, preserving its independence and neutrality. However, the dismantling of the fortress weakened Luxembourg's defenses, making it vulnerable in future conflicts, most notably during World War I when German troops occupied the country in violation of its neutrality. The Treaty of London of 1867 remained in effect until it was superseded by new agreements after World War I.