Final answer:
In 'All Quiet on the Western Front,' the older soldier with front line experience is Stanislaus Katczinsky.
Step-by-step explanation:
In the book All Quiet on the Western Front, the older soldier with front line experience is Stanislaus Katczinsky. He is a savvy and practical soldier, often referred to simply as Kat, who has a talent for finding food and other comforts for his comrades, revealing his resourcefulness and experience in such a brutal environment. The character serves almost as a mentor to the younger soldiers, including the novel's protagonist, Paul Bäumer, offering guidance and support as they navigate the horrors of trench warfare.