How Camp Amersfoort National Monument attracted 30% more visitors with a podcast campaign

10 January 2024

With the podcast campaign The Missing SS Commander, iO and National Monument Camp Amersfoort succeeded in creating the branded podcast of 2023. Staggering download figures, rave reviews from listeners, an important contribution to Dutch war history and a 30% increase in visitors. Here are the important lessons we learned making the most celebrated Dutch branded podcast of 2023 in a long read.

Podcast opname de verdwenen SS'er

Podcasts have been around for a while, and so have branded podcasts. But if we are honest, you can count the really good and impactful branded podcasts that are released in one year on the fingers of both hands. Agencies, like ours, have been preaching the gospel of audio-on-demand for years.

Podcasts: A Branding Rarity

Sometimes you get the opportunity from a brand to create a really fantastic series. The Guide, War Wound or Het Spoor Bijster for NS. But often branded podcast series end up somewhere in a forgotten corner on Spotify and Apple Podcasts, because insufficient budget makes it impossible to bring the best ideas to life and/or because there is no faith in audio as a medium (yet).

Maybe brands are spoilt, because short copy/video and a solid paid campaign behind it, offers certainty in content marketing. This isn’t terrible, don't get me wrong. But making an authentic impact often doesn’t happen.

Requiring and Maintaining Attention

Then take the medium of audio. Podcasts have so much to offer. Do you want to reach your target groups while they are in the car, on the train or on a bicycle? Whether they’re exercising, cooking, ironing, walking, gardening or just chilling? At all these moments, there is really only one medium that you can use to reach these 'moving consumers': podcasts.

On top of that, you have to pay attention to audio. And, compared to other media, you get a lot of time. Usually something like 20 to 30 minutes per episode. Try to achieve that on YouTube or social media. With a podcast, your target audience is feeding their imagination. Podcasts for brands. Branded podcasts give organisations the opportunity to stand out with a unique and authentic story, an exciting quest or by sharing relevant knowledge.

Leverage the immersive nature of audio to connect with your audience during a variety of activities, creating deeper engagement.

The Missing SS Commander: The Beginning

National Monument Camp Amersfoort believes in podcasts.

In March 2022, I met director Micha Bruinvels and head of research Floris van Dijk for the first time in the renovated museum of Kamp Amersfoort. An impressive place that, as a resident of Amersfoort, I know mainly from the outdoor area. The renovated underground museum has not been open for very long. It was opened in the period we would most like to forget: corona. And the question for us is clear: how do you encourage people to visit your museum? How can we combine physical and digital experiences so that they complement and reinforce each other? How do you share a real story with a wider audience and stimulate the interest of potential visitors?

A choice of 47,000 stories

A podcast is the medium of choice to tell a complex story about true events. We quickly agreed on that. But in a special place like Kamp Amersfoort, there are at least 47,000 stories to tell. Several of them have already been highlighted in the museum. The question: how do you get all the stories in a podcast series? The answer: you don't.

The podcast excels when it comes to explaining one story in detail. But what story can we highlight in a museum? And do you tell a story that can also be found in the museum, or not? Are you looking for a theme?

Embrace the uniqueness of podcasts. Choosing the right story has a strong impact on its success. So, reserve enough time and attention for this.

This is it: the mystery of Walter Heinrich

To get an even better feel for Kamp Amersfoort, Floris gave us a tour. The feeling you get in the new underground museum is unavoidable and immediate; depressed. You feel the war and the harshness of life in the former concentration camp. It didn’t immediately provide me with any usable insights for a podcast.

We took the stairs back up to the outside area, where you are directly confronted with the 'shooting range'. And a conversation ensues about Floris’ current research. He got hold of the first camp commander of Camp Amersfoort’s SS file. While most people know camp commander Karl Berg and his deputy Joseph Kotalla, the name Walter Heinrich has fallen into oblivion. Yet he was the founder of the camp. And, Floris says, he was never tried, the only camp commander based in the Netherlands who was never prosecuted. In fact, he mysteriously disappeared.

'This is going to be it', was my firm conviction right from that moment. This is going to be a podcast hit. There is no other way... Micha and Floris were also convinced. Let's go for it.

Quali time

Floris and I immediately dived into a plan of action. How will we find out what happened to this camp commander? What had Floris already figured out? What clues and leads did we already have? We started with an editorial meeting, and once again reviewed possible hypotheses. Then we made a plan. The period that followed was mainly a historical investigation.

The role of chance

You can listen to this research in detail because that became the podcast. But I've learned one thing: Historical research often depends on coincidences.

Because if I hadn’t met the friendly lady in the Staatsanwahlt in Bremen, we would never have known of the existence of Walter Heinrich's son. If Floris hadn't been digging through the NIOD again, we would never have known that Heinrich is an even bigger war criminal than we thought. If I hadn't found a prominent historian on internet forums who had seen the name 'Walter Heinrich' in one of the many interrogations from '45, we would never have ended up in Karlovy Vary, in the Czech Republic.


You won't always be able to script a podcast completely. I'd rather not. Especially if your storyline is based on (historical) research. That often depends on serendipity. Be open to this and embrace unexpected events and the nuances of your journey. This increases the chance that your listener will do the same and provides opportunities for making your story attractive.

Walter Heinrich's Dark Role Revealed

By being meticulous with this historical research, we unearthed revelations, with impact and news value.

Walter Heinrich founded Kamp Amersfoort. He ruled with an iron fist and was implicated in the execution of Soviet prisoners of war. But now we also know, thanks to our research, that he was stationed in The Hague in 1943, at the office of the Befehlshaber der Sicherheitspolizei und SD, charged with making resistance fighters disappear under the ‘night and fog’ regulations. He is also involved in the deaths of more than 650 people.

Research shows that his children are still alive. And his final destination was not living a life of luxury in Brazil, but most likely a Czech spa or a Gulag because he was eventually apprehended by the Red Army.

Kamp Amersfoort

Going live #1 and #2: the growth of a podcast hit

The podcast went live on October 4, 2022. From the start we had around 1,000 downloads per day. Not surprising but come on: this is about a camp commander who turns out to have even dirtier hands than initially thought. A story that was picked up by the Dutch media, with Trouw, NOS, Op1, Humberto and Khalid and Sofie.

Our PR efforts payed off. On 7 October, Trouw published Walter Heinrich's news in the morning newspaper and at the top of the homepage. Radio 1 invited Floris and after the broadcast on the story is on the three most featured articles on the homepage for hours and (as a child of the 80s and 90s I think that's great) we were on Teletext 101.

You can't just put your podcast online and hope it becomes successful on its own. People should have the opportunity to discover your story. Strategic PR deployment can give your podcast's reach a serious boost. Also consider the use of media partners and, for example, social media. If you interview famous people in your podcast, ask them to share the podcast via their own channels after it goes live.

You can also take this into account when choosing your story. A story that is newsworthy can ensure that your podcast is put in the spotlight with organic coverage.

Kamp Amersfoort
From downloads to national media coverage

From that moment on, we had 10,000 downloads per day, in the top 10 of the podcast charts, regional media also interested in our production and the first fan mail hit our mailbox with tips on where we should look next.

By the end of December, we were on 400,000 downloads. We are still at the top of the charts and thousands of downloads are added every day. But the story is far from over. Floris and I get to see new documents and facts. In addition, Walter Heinrich's son invited us to visit him. The impressive episodes 7 and 8, a journey through Germany and the Czech Republic, provide a satisfying conclusion to the series.

What followed is renewed attention in the national media. On Sunday evening, March 26 at 8 p.m., we proudly watch the NOS Journaal with Rob Trip. A cherry on top of the icing on the cake, that took our story to 2.4 million TV viewers.

NOS news broadcast about this podcast


iO and Nationaal Monument Kamp Amersfoort created an eight-part podcast: The Missing SS Officer. A poignant audio story that has been listened to almost a million times.

The results?

Now more than a year later, the counter now stands at 1.3 million downloads. The average listener rating on both Spotify and Apple is a 4.7 out of 5. We’ve achieved a record number of 15 awards at national and international award shows.

We have given a face to a relatively unknown war criminal and unearthed important facts for our post-war history. The Sound and Vision Foundation in the Netherlands wants to include the podcasts The Missing SS Commander, as well as War Wound in their historical archive for posterity. The impact we have achieved with this podcast is immense.

The numbers


million downloads


both Spotify & Apple score out of 5




more visitors
The effectiveness of a podcast campaign

We are most proud of the fact that this beautiful digital audio product has led to more physical visits to the museum. And not just a few more. More than 30% more visitors have been registered since the podcast went live. Belgian visitors even come to the museum because they were so impressed by the podcast. The posters that point people to the podcast in the restaurant of Kamp Amersfoort are so popular that visitors ask how much they cost. It led to a discussion about whether we should consider manufacturing more merchandise to accompany the podcast.

Just kidding, of course. But the reality is that this podcast surpasses any branded podcast in terms of performance and returns. Impact, appreciation, but above all effectiveness. 30% more customers, thousands of visitors who all buy tickets, have a cup of coffee and cake in the café. And all of this because we made a podcast that hit the right note with jury members. The highest praise from a jury member who said: 'This is a production of a level that you usually only see on the public broadcaster.'

Don't forget to measure the impact and effectiveness of your podcast. This can provide you with valuable insights into how your podcast is performing, where you may need to make adjustments, and how it can be improved. After all, you've invested time and resources in it; Then it's also good to know what it yields and how you can get the most out of it.

A collaboration for the best stories

The great thing about working with Kamp Amersfoort is that we are all pursuing the same goal. To create a story with impact. Micha is an inspired director, whose grandfather was murdered eighty years ago in the Dorohucza SS labour camp. He is also a podcast fanatic. Floris is a historian with an enviable knowledge of the Second World War. Ask him what happened on March 13, 1943, and he will undoubtedly rattle off important facts from WWII in his characteristically sympathetic narrative style. And as a podcast maker, I'm primarily a storyteller. The three of us constantly challenged each other, fought over details, had discussions. But we kept it civilised.

It has led to an audio product that would have sold the Philips Stadium out 12 times over, in terms of unique reach. And the great thing is, we have now managed to attract so many subscribers that our next podcast will likely be another hit.

How do you link a brand to a podcast?

In both content marketing and podcast marketing, you try to make a link with the brand, in this case Camp Amersfoort. There should be no doubt as to who is delivering the podcast. The brand should benefit from their investment in content. With advertising, it's always easy. With content, that game is a bit more layered. But with the right design, solid branding in social updates, and the right balance in all content output between the programme brand The Missing SS Commander and Kamp Amersfoort, it all worked out fantastically.

For content marketers, that element of the game is often the hardest part. Brilliant content goes a long way, but that last bit – linking the content idea to the brand – is artisanal tinkering with a potentially big return.

Kamp Amersfoort and iO eventually linked a face and a story to a war criminal who was unknown in the Netherlands until now — and we filled in a number of large gaps in our shared history and knowledge. In this way, we have not only boosted the profile of the museum and increased engagement and visitor numbers, but I also think — although you have to be careful with these kinds of statements — that The Missing SS Commander is the best branded podcast in the Netherlands to date.

Connect your content to the brand. Effective design, social updates, and maintaining a balance between the content brand and the overarching brand can accomplish this.

Take-aways from the most celebrated branded podcast

  • A good podcast takes time. Take your time. Invest in that as well. Of course, looking for a missing Nazi is not on topic for most parties, but that does not mean that imitating celebrity podcasts will be the easy answer.  

  • Newsworthiness is the best way to produce a hit. Ok ok, getting a slot on the most watched Sunday evening news should not be the goal, but winning podcasts go viral after getting on the news organically.  

  • It’s not about you. Podcasting without thinking about the listener, puts podcast listeners off. That may feel like a barrier for marketers. But National Monument Camp Amersfoort can tell you all about it. Walter Heinrich still plays virtually no role in the museum. Purely because we didn't know anything about him until our podcast and the museum is a permanent exhibition. But is that a bad thing? On the contrary, choosing 1 story stimulates the interest in finding out more. 

  • Consistency in frequency of release. The Missing SS Commander was released 2 to 2. So, two episodes every week. The advantage of this method is that listeners continued to listen but came to expect new episodes at a fixed time.   

Listen to the podcast on Spotify:

Branded podcasts

A strong branded podcast starts with identifying the best stories, coming up with the right format, and choosing the most effective release frequency. iO will guide you through the process.

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