Mine would date to 1956 or 57, but I'm sure they would have been in use in WWII. I don't know about WWI though, but logic would make me think they had them then. Pocket knives go way way back, and I and would think the need for marlin spikes goes just as far back. But your find looks to be stainless, and if that's true, then it has to be more modern. I know they had stainless knives in the 50's, but to me the steel wouldn't hold an edge, and I liked Case knives the best. One thing that is kind of interesting. Cutting manila line with a sharp blade is mission impossible. I didn't mess mine up, but a couple of first class boatswain mates wanted me to knock notches in the blade, because it would then act like a saw and cut the line. I don't know if that's what happened to yours, but like I said, I didn't do it to my knife. Frankly I didn't work with manila line that much anyhow. It seems to me most line I worked with was already made up by someone else. We did make some hemp fenders, and I worked with wire some, splicing eyes mostly.