It was due to its ideal geographical location that Gemundia was to develop. In the 8th Century it was little more than a large sized farm situated at the confluence of the Sarre and the Blies rivers. However, the existence of a stream and the need to create a North-South-East-West crossroads gave the site a strategic importance. The result was the rapid fortification of the farm which then gave way to a castle which dominated the Sarre valley up until the 13th Century.
The seat of a seigniorial domain under vassalage to the dukes of Lorraine, Sarreguemines asserted its military nature, began to establish the first legal and fiscal structures and little by little began to impose its authority on the surrounding villages. With the granting of a franchise charter in the14th Century, Sarreguemines threw off its feudal yoke and became governed by an autonomous municipal body. The town was then able to develop in three main directions, militarily, administratively and commercially, although this new found prosperity was to often suffer setbacks owing to the wars and plagues which regularly ravaged the region.
In the middle of the 18th Century, territorial reform and exchange treaties between France and the German princes harmonised the limits of legal and fiscal jurisdiction, and a homogeneous group of villages grew up to be administered by Sarreguemines.
Trade was to experience a vital boost thanks to the import of wood from Holland, the local textile industry, and the addition of a new business sector: pottery.
The Treaty of Vienna (1815) put Sarreguemines in the position of facing up to the arrogant Prussians. Local history was to be strongly influenced, the Lorraine town became the hub for exceptional economic dynamism and resulted in the apparition of the "great industrial Barons" such as Utzschneider, Geiger, Jaunez, and Huber. They were to open up the region thanks to the creation of new communication channels (canals, roads, railways) and the town experienced a previously unheard-of level of prosperity. Tall chimneys towered over the roofs of the factories in which the labouring population worked. In 1850, Sarreguemines was populated by less than 6,000 people, by 1900 this figure had reached over 14,000, and a century later it had risen to 23,000 !
At the end of the First World War, the nearby carboniferous basin became the spearhead of the regional economy whilst the Sarreguemines basin suffered from the effects of being so close to the enemy country. The Maginot Line turned it into a border town that acted as the defender of the French Homeland, a role that the town was eventually to play. Traumatised by the Second World War of 1939-45, Sarreguemines was only to drag itself out of the doldrums little by little.
This was followed by the reconstruction period which enabled an urban restructuring more suited to modern requirements. Sarreguemines' reputation had for a long time been centred around its construction companies and, although it was sad to note that its traditional sectors were in decline (textiles and ceramics), its industrial renewal firmly established itself in the 60s'. Little by little the idea of a "Common market" took root and the town’s closeness to Germany opened up promising prospects for growth in both economy and trade