Aloyse made his first military experience in 1935, at the age of 15. Back then, he joined the Légion étrangère, serving for three and a half years before returning home.

In Luxembourg, he retook military service and joined the Luxembourgish Volunteer Company on 11 October 1939. Following the Nazi invasion of Luxembourg in 1940, Aloyse was sent to Weimar for further military training and ideological reeducation. He was later transferred to Hamburg and forcefully conscripted into the Division “Germania” of the Waffen SS. In March 1942, Aloyse was discharged in Klagenfurt, Austria. Apparently having simulated a heart condition, disabling him from military service, German SS officials sent him back to Luxembourg.

Between 1942 and 1944, he worked for a farmer in Ettelbruck and joined the local resistance group “Lëtzeburger Ro’de Lé’w” (Luxembourgish Red Lion). He helped to supply resistance fighters and draft dodgers with food.

After the Allied victory over Germany in 1945, Aloyse joined the Luxembourg Army in June and was attached to the 3rd Company of the IInd Battalion. 

Following the breakout of the Korean War, Aloyse signed up as a volunteer to the Luxembourgish contingent. Ranked Sergent-Chef, he became the leader of a combat section.

Aloyse and his section earned a citation from Belgian Colonel Albert Crahay for their bravery on 23 April 1951, while fighting at the Imjin River. During a counter offensive, they managed to free a group of 15 Belgian soldiers encircled by a Chinese unit. Despite his undeniable military knowledge, his personality was not unanimously appreciated within the Luxembourgish detachment. His subordinate, Caporal Jean Stoffel, frequently expressed harsh criticism, stressing his frustration with Aloyse’s leadership and strategic abilities as a section leader.

After his return to Luxembourg, Aloyse remained in the army until his retirement in December 1970.