Aim: Conduct an analysis and provide a pathophysiological justification for the case of the formation of an ulcer of the duodenal bulb in a 27-year-old soldier of the Armed Forces of Ukraine. Materials and Methods: After collecting the anamnesis, the patient underwent a comprehensive examination, which included step-by-step pH-metry, esophagogastroduodenoscopy, testing for Helicobacter pylori infection (HP) (urease test and microscopic examination of stained smears-prints) in 4 topographic zones of the stomach, and histological examination of the gastric mucosa in the same zones. Results: When collecting a family history, it was found that relatives on one male line - father and grandfather - suffered from ulcer disease. It was established that on the eve of an exacerbation, which lasted 3 weeks, the soldier helped load a car, repeatedly lifting boxes with ammunition up to 20 kg to a height of 1.5 m. During pH-metry it was found that the acidity level of gastric juice corresponded to the basal normacidity of total. During esophagogastroduodenoscopy the following diagnosis was made: “Ulcer of the duodenal bulb in the active stage (in the middle third, along the back wall, 1.5 x 0.8 cm, the ulcer defect is covered with gray fibrin). Erythematous duodenogastropathy. Indirect signs of pancreatopathy.” The presence of chronic gastritis in the active stage in the patient was confirmed by the results of histological examination of the gastric mucosa. The type of gastritis (non-atrophic) was confirmed by testing for HP infection, which revealed a high concentration of the active form of bacteria - (+++) in all 4 topographic zones of the stomach. Conclusions: Stress associated with participation in military operations led to the active reproduction of Helicobacter pylori infection and, accordingly, an increase in “residual” ammonia in the stomach cavity. Heavy physical exertion, which was accompanied by a sharp contraction of the muscles of the anterior abdominal wall, created a “bellows” effect, which concentrated the “residual” ammonia in the cavity of the duodenal bulb and led to the formation of an ulcer.