⏵ Course guide · Northern Virginia loop ultra
Devil Dog Ultras runs 100 Mile, 100K, and 50K loop races through Prince William Forest Park, across the street from Marine Corps Base Quantico, on a 23 mile first loop followed by repeated 19.5 mile loops. I will walk you through the loop structure and aid stations first, then give you a pacing and fueling plan built for a cold December loop race. There are free calculators along the way to dial in your own numbers.
These facts come from the official devildogultras.com site. Check the current year details before you commit. Race logistics can change year to year.
All three distances share the same loop system through Prince William Forest Park, primarily single-track with occasional roots, rocks, and brief technical sections.
The first loop runs 23 miles, and every loop after that is 19.5 miles. That means your early splits will not match your later ones simply because the loop length itself changes, something worth planning for rather than being surprised by mid-race.
The 50K combines a single 23 mile loop with a shorter 9 mile "puppy loop" tacked on, giving newer ultra runners a taste of the full course's terrain and aid layout without committing to the repeated-loop grind of the 100K or 100 Mile.
Every full loop passes three fully stocked aid stations, Camp Remi (also start/finish), Camp Gunny, and Camp Toofy, plus three unmanned water-only stations, RP Alpha, Bravo, and Charlie, for quick top-offs in between. That is frequent enough support to run light between full resupply points.
The published time limits give real structure to build a plan around: 10 hours for the 50K, 20 for the 100K, 32 for the 100 Mile.
Since the opening loop is 23 miles and every loop after is 19.5, do not judge your race off a single blended per-mile pace. Use the race-time calculator to check your projected finish against the published time limit for your distance, treating the first loop as its own segment.
Primarily single-track terrain with only occasional technical sections is runnable, which makes it tempting to go out too fast on the early loops. Use the race-equivalent calculator to translate a recent long effort into a realistic per-loop split you can actually repeat for 20 or 32 hours.
⏵ Free tools to plan your effort
Six aid points per loop make Devil Dog forgiving to fuel, but early December in Virginia adds a real cold-weather variable for the 100K and 100 Mile.
Three fully stocked stations and three water-only stops per loop mean you rarely go far without support. Aim for roughly 60 to 90 grams of carbohydrate per hour while moving and sodium in the 300 to 700 mg per liter range, and if you are running overnight for the 100K or 100 Mile, plan warm layers and possibly warm fluids for the coldest hours.
With loops passing through Camp Remi, the main start/finish aid station, repeatedly, a drop bag there gives you a reliable place to change layers, restock, or swap gear as December temperatures drop overnight.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight and your own target distance with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a training plan built around YOUR fitness and this 23-then-19.5-mile loop structure, whatever distance you choose. Summit Line reads your real training, builds the repeatable pacing this course demands, and rehearses your fueling so race day is something you execute, not guess at.
It scales with distance but is a real test at every one. The course is primarily single-track with occasional roots, rocks, and brief technical sections rather than sustained mountain climbing, but the loop structure, a 23 mile first loop followed by repeated 19.5 mile loops for the 100K and 100 Mile, means fatigue accumulates over genuinely long stretches between full aid resupply.
The published time limits are 10 hours for the 50K, 20 hours for the 100K, and 32 hours for the 100 Mile. With the 100 Mile and 100K starting at 6:00 AM and the 50K at 7:30 AM, those windows set your overall deadline; confirm any intermediate per-loop cutoffs directly with the race before you finalize a pacing plan.
The first loop runs 23 miles, and every loop after that is 19.5 miles. The 50K is built from one 23 mile loop plus a shorter 9 mile "puppy loop." Three fully stocked aid stations, Camp Remi (also the start/finish), Camp Gunny, and Camp Toofy, sit on every full loop, plus three unmanned water-only stations (RP Alpha, Bravo, and Charlie) for quick top-offs between them.
With three fully stocked aid stations on every loop and three additional water-only stops, you have frequent resupply options for a December race in Virginia. Aim for roughly 60 to 90 grams of carbohydrate per hour while moving and sodium in the 300 to 700 mg per liter range, and build your own numbers with the free ultra fueling calculator, factoring in cold overnight temperatures for the 100K and 100 Mile.
Primarily single-track trail in Prince William Forest Park, with occasional roots, rocks, and brief technical sections rather than constant technical footing. This makes it a runnable course by ultra standards, where pacing and loop-to-loop consistency matter more than surviving any one brutal stretch.
The 50K, built from a 23 mile loop plus a 9 mile puppy loop with a 10 hour cutoff, is a reasonable step into the event's loop format for a first-timer. For the 100K or 100 Mile, primarily single-track terrain with only occasional technical sections is on the more approachable end for the distance, but the repeated 19.5 mile loops and overnight December cold still demand real ultra experience and sleep-management planning before you commit to either.
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<a href="https://runsummitline.com/guides/devil-dog-ultras">The Devil Dog Ultras course guide</a><iframe src="https://runsummitline.com/embed/race/devil-dog-ultras" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="Devil Dog Ultras course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, and cutoffs come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.
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