The Royal Marine who helped save the Peruća Dam

INTERVIEW - Col Mark Nicholas Gray, (Ret.) British Royal Marines

Alongside the members of the Croatian Army, a huge contribution in preventing a major catastrophe on gravely damaged and mined Peruća dam back in 1993 came from the British member of the UN Military Observer Team, Capt. Mark Nicholas Gray, who was 26 at the time. He realised the imminent risk with possible fatal consequences and let go the sluice gate on the upper spillway, thereby reducing the risk of overflowing the area downstream. The sluice gate was kept open enabling constant flow of the water and maintained the dam level about 5 metres below full, easing the water pressure on the dam and averting a looming disaster.

What was your role and the role of the UN observers in 1991 related to the area of the Peruča power plant?

I joined the UN mission in July 1992.  Having completed my UN induction training I was invited to form part of a new (unarmed) UN Military Observer (UNMO) team to be based in the Sinj area.  The concern of the UN at the time was that in the so-called Pink Zones, the two combatant parties were separated in many places by only a few hundred metres.  The proximity inevitably led to ceasefire violations between the parties, which eroded trust, exacerbated tension and threatened the peace that the UN was trying to build. 

Our role was to police the Pink Zone around Sinj, develop confidence building measure between the sides and ultimately encourage withdrawal by both sides to generate buffer zones that were greater than the range of small arms.  This was achieved by constant patrolling on both sides (we were the only UN forces who were routinely permitted to cross the front lines and operate on both sides), visiting front line troops, monitoring the storage of heavy weapons, investigating ceasefire violations etc.  We also, for example, collected the bodies of fallen soldiers lying in no man’s land so that families could bury their loved ones.  While we were establishing the office at that time, we were exposed to the situation at Peruča and specifically the twofold concerns of those on the Croatian side.  These were firstly that the dam sluices had been fully closed up and no water was passing through, denying water to those downstream on the Croatian side (the dam sits just the other side of the then ceasefire line, so was controlled by the so-called RSK forces, while flowing to the Croatian side), which was causing issues in water supply; and secondly there was a growing fear that with the reservoir being unusually full, the expected autumn rains might overfill the reservoir and cause the dam to overflow – a fatal event for an earthen dam like Peruča. 

Initially the officers of 126 Brigade (specifically the Brigade Commander, Colonel Rahim Ademi and the Liaison Officer to the UN Major Vlatko Bandalo) made our team aware of these issues and invited us to meet with the previous manager of the dam, Mr. Josip Macan (who had not visited the dam for some time).  I then met with Mr Macan on many occasions as he struggled to instruct a simple Marine in complex dam technology and maths.  Over a number of meetings, Mr Macan impressed upon me the risk to the dam and the importance of monitoring daily the height of the water.  At that point we started taking daily readings and in our reporting were transmitting the concerns of the Croatian side to our superiors in the UN organisation.  The points were well made and the UN hierarchy commission two dam experts from Ireland to come out and inspect the situation at the dam.  I hosted their visit and took them to the dam and also enabled them to meet Mr Macan; they returned to Zagreb and reported to the UN Force Commander (Indian General Satish Nambiar).  He accepted their recommendation that the Sinj Office generally and me in particular were given special responsibility for the dam.

 You realised the imminent risk and the importance of preserving the dam. What steps did you take in that regard in order to prevent a major disaster, the demolition of the dam and the flooding of the surrounding areas?

With the new responsibilities, we took on the role of daily measurement and an attempt to persuade the RSK forces on the dam to release water.  The lieutenant in command of the platoon on the dam referred our requests up his chain of command, and rejected it.  We then set a priority of releasing water from the dam, to reduce the autumn risk.  At the same time, we had learned of a growing concern that the RSK may have rigged the dam with explosives.  While RSK forces occupied the dam this was impossible to prove, but the UN was putting immense political pressure on the Serbs to hand over control of the dam to the UN.  While this was going on, I took the opportunity to try and release water from the dam, by letting go the sluice gate on the upper spillway on the right hand side for the dam.  Mr Macan had explained to me the mechanism for releasing it, despite the fact that the machinery had been destroyed.  The sluice was held shut by an iron bar in a cog wheel and releasing it was as simple as pulling the bar out.  One day I simply strolled past the burly Serb guards and pulled the bar out. 

The water pressure pressing on the sluice then pushed it open, releasing millions of gallons of water for the first time in months.  The Serbs reacted angrily, but there was nothing that they could do, other than wait for it to open fully and then start to crank it back up.  Due to the war damage, this could only be done manually, and took the whole platoon about 8 hours to achieve.  The following morning I went back and did exactly the same thing.  They were a bit cross and didn’t even offer me tea!  Again they cranked the gate up again over much of the rest of that day.  The following day they made certain I could not get to the gatehouse, and over the following few days, we paid a game of chicken, whereby I would pop over and try to get to the gatehouse, while the biggest of the big Serb soldiers barred my way.  In the end I got there again and got the sluice open at around the day that agreement was reached that the RSK forces would pull back and hand the dam over to the UN.  At that point they did not bother to lift the sluice gate again, and it remained open from that point until the dam was blown, thereby maintaining the dam level about 5 metres below full – a significant amount because the height of the inspection tunnel through the middle of the dam was only two metres.

Combined with the Irish experts’ report and voiced concern in the UN Security Council, the Serbs did agree to hand over the dam.  However, for some, this was done perhaps a little too easily, and there was a suspicion that they held an ace in their hand.  Many on the Croatian side had heard rumours, and believed that the Serbs had placed explosives in the inspection tunnel of the dam.  This was uncorroborated, and we had no way of finding out, while the Serbs were in control. Once they had agreed to give up the dam, and the UN took control, it became important very quickly to establish two things – had the Serbs rigged the dam to blow; and if so, could they blow it remotely, or did they have to return to the dam to achieve this (i.e. plant detonators).  The UN taking control of the dam, in theory should have made life much easier, but in practice, the Kenyan battalion tasked with the occupation, was far more restrictive to us (the UNMO team) than had been the Serbs.  It was all very frustrating.

Therefore, my goal in getting the sluice gate open was to reduce the risk that the dam would overflow in the autumn. Getting it open and keeping it open was a major achievement – it gave the Croatians downstream their essential water (which also fed hydroelectric plants downstream and gave electricity) and significantly removed the risk of flooding and dam destruction.

 You delivered the documents and dam project to the Croatian Army, as well as the intelligence data on the mines planted and exposed yourself to a serious risk, as the dam had been occupied by the aggressor army. How do you comment on that?

As far as the documents were concerned, Mr Macan asked me very early on if I could access the dam’s library which contained all of the plans and tables which allowed them to calculate the risk.  While Mr Macan knew the dam very well indeed, he had not memorised the hundreds of statistical tables needed to operate it safely.  He asked me to check the respective offices, and I went in and photographed the whole area early on, with the Serbs in control.  I showed the prints (this was before digital media!) to Mr Macan, who then identified which of his publications he needed.  In the end I brought most of the library out, over four or five trips without the Serbs being aware (they never had anyone manning the main hydro plant buildings, for some reason – they just protected the top of the dam, and the buildings there).  I delivered the documents to Mr Macan’s office in Sinj centre having taken them across the front lines.

As far as the explosives were concerned, as I said, it was critically important to the UN to identify the state of the dam.  Of course, no-one in the UN would dream of ordering us UNMOs to have a poke around, but the importance of doing so was immeasurable.  Once the dam had been handed to UN control, it was important to find out the facts, and there was lots of faffing around while decisions were made in Zagreb and people were being sought.  In the end myself and another team member, Maj Carlos Maas, a Brazilian military engineer, decided to go down to the inspection gallery and see what we could find.  In doing so, our concern was that the explosives, if there, might have been booby trapped and our greatest concern was from a light sensitive detonator.  For that reason we went down with very dim red light torches only.  Carlos led the way (he was the engineer) and I cowered (a long way) behind him.  We tip-toed into the tunnel, entering from the right hand entrance, and largely felt our way in through the entrance tunnel, turned left and started descending the wet, slippery steps in the dim half- light cast by our red torches. 

When we got to the bottom we could make out large rectangular boxes placed at the bottom of the tunnel.  They were not something that either of us recognised, but we could make out the word UDAR written on the side in both Latin and Cyrillic (УДАР) scripts. We sensed it was some kind of explosive, and we totalled the number of boxes, leaving hastily when we had done it, careful to check whether there was any form of command wire running up the steps (there was not).  We had a good look around the top of the dam, again checking for command wires, or unusual antennae.  We could see neither.  As a result of this visit, bravely led by Carlos (who is barely mentioned or recognised for his critical role in this, much to my dismay – he is now a General in the Brazilian Army) we were able to determine that the dam was rigged with a special kind of Yugoslav fuel-air explosive, sufficient to cause dam collapse and that it probably required the Serbs to return to the dam to prime the explosive charges.  This was critical information because we (the UN) knew that the dam was safe if the Serbs could not get back to it.  We passed this information back up the UN chain of command, and also informed Brig Ademi.  The UN then subsequently sent a UK Royal Engineers team to look at the dam, and they confirmed our conclusion.

December 2020 saw the verdict to the commander who ordered explosive activation which destroyed the dam. What is your comment on that??

There is no question in my mind that the rigging and blowing of the dam was a war crime of the most heinous kind.  Somebody ordered that to happen and others executed the order.  The act is a serious breach of the Geneva Convention and even 25-30 years later it is vitally important that the perpetrators are found and tried.  These people exist and Nuremberg showed that you cannot hide behind the defence of “following orders”.  They were soldiers, they knew what they were doing.  They must face justice.  The outcome of the trial is less important to me, just that they face justice.  Croatia is a first world European state, whose justice system is fair and impartial.  If the accused are found not guilty, so be it, the judicial process has been enacted.  If they are found guilty, they must serve an appropriate sentence, determined by the judge.  The success is getting the accused into a courtroom – the world is well served by this outcome.

Looking back on that time today, what is your view of your participation in the events and of the fact that the international community did not do much for Croatia then, and that the examples such as yours were a rarity, but won deep respect and gratitude.

From today’s perspective my views on the events would not perhaps be as negative as you portray.  The world in general and Europe in particular were blindsided by the German recognition of Croatia’s declaration of independence from Yugoslavia.  It kicked off a chain of events the world was unprepared for.  UNPROFOR was the first of the modern UN missions and for everybody it was a learning curve.  For me, a young and junior officer, despatched largely unsupervised on a task requiring intelligence, initiative, diplomacy, wit and humour, dogged determination and oodles of enthusiasm, it brought the risk, reward and adventure that I had joined the military for. 

The international community in general and the UN in particular were still finding its feet and made some errors.  For example, the impression of impartiality, in UN eyes, was critical to the success of the mission and it seemed (to me at least) to trump basic humanitarian considerations, which I found frustrating; this was seen by the Croatian side as the international community “turning its back on Croatia”.  People within UNPROFOR were committed and dedicated, but UNPROFOR was different and did not follow previous models, and so policies evolved.  We got lost wrong, but we did much that was good. People did their best in extraordinary times.  For me it was easy, I just did what I thought was right at the time.  I knew I was there to save lives, and that was always my focus. 

I was never in doubt; in my own mind that is, as to what was the right thing to do in any circumstance.  I did not consider personal risk, I was young and it did not matter; doing the right thing did. And it is easy to forget the humanity – in these scenarios you deal with people, human beings, who think and feel and express.  When you watch the news, it is cold, humanity is removed; events are strategic, politicians are the stars.  But the stuff always happens on the ground, with human beings and humanity on both sides of a fence.  Ordinary people who are suffering through circumstance. 

Helping them, improving their lives, even preserving their lives is the important thing.  We are all ordinary people in our hearts and it is for the extraordinary, ordinary people on both sides of the conflict that I worked.  I do not think I was unique in that.

You have received decoration for your part in the protection of the dam and prevention of demolition of the dam. What does the decoration mean to you as the witness of the time? 

 I was incredibly honoured and humbled to be recognised by President Josipović, on behalf of the Croatian people, being appointed to the Order of Duke Domagoj.  For me, it was enormously rewarding, although my part was small. Nevertheless, I was the only one recognised and feel slightly fraudulent.  Immense contributions were made by, in no particular order, Mr Josip Macan, Maj. Vlatko Bandalo, Maj Carlos Maas, our team interpreter, Ivan Šušnjara (who did not simply “translate” but understood all of the strategic complexities of the situation and was a great sounding board for ideas, and prodded, poked and cajoled us all the time), the 126th Brigade engineers, the whole HEP team – I could go on. The medal I am privileged to hang around my neck was earned by all of them.

Croatian version:

Kraljevski marinac koji je pomogao spašavanju brane Peruća