À la suite was a military title, given to those who were entitled to wear a regimental uniform but otherwise had no official position. It can best be translated as "in the entourage of".

In Prussia

Prussia

Prussia was a German kingdom and historic state originating out of the Duchy of Prussia and the Margraviate of Brandenburg. For centuries, the House of Hohenzollern ruled Prussia, successfully expanding its size by way of an unusually well-organized and effective army. Prussia shaped the history...

, these were:

• À la suite of the army - for example granted to such officers, who came to command non-Prussian battalions at certain higher ranks, to guarantee their advancement in the Prussian army
  Prussian Army
  The Royal Prussian Army was the army of the Kingdom of Prussia. It was vital to the development of Brandenburg-Prussia as a European power.The Prussian Army had its roots in the meager mercenary forces of Brandenburg during the Thirty Years' War...
  
  
• à la suite of regiments - for example princes and generals as a special honor, or officers who commanded non-Prussian battalions.

Officers and others (for example surgeons were "à la suite of a Sanitätskorps") were thus not inserted into the military command structure, but rather had roles in the administration, military direction (war ministry, or similar) or military education. Also men could be "à la suite of his majesty" if they directly worked for the ruler.