In hindsight, Gloucester never really looked particularly troubled despite the close scoreline, but were forced to fight for their lives in the final quarter.
The Cherry and Whites pretty much monopolised territory and possession against a side occupying 14th and last place in the Top 14 but, largely due to the foul weather conditions, couldn't finish off the chances they fashioned.
It resulted in a tense, hard fought encounter - one that took an unexpected turn just before the hour mark.
Referee Neil Hennessy was already having to work hard to keep control of a game which looked as though it was set to explode, with the hosts seemingly indulging in a certain amount of off the ball activity.
Scott Murray had been yellow carded for persistent infringement in the first half and was followed by replacement hooker Ephraim Taukafa after the break.
But it all kicked off just before the hour when Andy Hazell reacted angrily to what looked like more off the ball provocation.
The flanker was pointing to his eyes but insult was added to injury as he was sent off for his retaliation. Team mate Matt Cox was yellow carded at the same time.
Gloucester now had to dig deep with thirteen men and then fourteen men after Cox's return. But, the Cherry and Whites are made of stern stuff this season and had enough spirit and application to close out the win.
The crowd at Stade Guy Boniface may have been a relatively small one but the atmosphere rose as kick off time approached with both sets of supporters trying to get behind their team.
Gloucester made a steady start with Tindall and Molenaar both carrying strongly and a penalty opportunity quickly presented itself. Tim Taylor had the distance but was narrowly wide.
At which point, the heavens duly opened and the home PA announcer received rapturous applause for announcing those on the terraces could sit in the main stand.
In the conditions, keeping it tight was always going to be a good option and a well executed catch and drive nearly led to a Gloucester score but a penalty was conceded for a forward going off his feet near the home line.
Minutes later, a strong break on the counter attack from Tindall made good ground, but the flying Ian Clark couldn't hold on to the pass as the first score remained elusive.
And frustration grew when Charlie Sharples latched on to a high kick from Tim Taylor in the home 22 but was hauled down just short, while a sparkling break from Martyn Thomas only resulted in a knock on.
Then, with 22 minutes on the clock, the Gloucester scrum won a penalty deep in the Mont de Marsan 22. However, Tim Taylor missed a relatively straightforward shot at goal. The home crowd were suitably encouraged.
The pressure didn't didn't let up and Scott Murray was sinbinned as a promising Gloucester attacking maul was pulled down.
It was the nimble feet of Dave Lewis that finally opened the home team up. A quick show and go and he darted around a ruck but couldn't quite make the line.
However, a cool head, good ball presentation and quick recycling saw Ian Clark scoot over in the corner. 5-0 after 30 minutes.
Gloucester had one more chance before half time but a catch and drive deep in the home 22 was penalised for a man in front of the ball carrier.
So, the Cherry and Whites went into half time with a narrow advantage on the scoreboard but having completely dominated territory and possession.
The conditions, admittedly, were a great leveller and a lot of possession near the Mont de Marsan line had produced relatively few points.
It wasn't pretty but Gloucester had their noses in front. What was required was a professional second half display to close this one out.
Gloucester had to endure some pressure at the start of the second half but the big forwards were quickly stepping up again, carrying with purpose into the home half. But, to be fair, the home tackling was admirably resolute.
Things were getting heated though and replacement hooker Ephraim Taukakfa had barely taken the field before being sinbinned for an off the ball incident.
Things were threatening to boil over but Tim Taylor settled things down with a 51st minute penalty for an 8-0 lead. However, this was instantly matched by a long range effort from full back Jean-Baptiste Claverie.
Still the aggro continued, and it was Andy Hazell who reacted to another off the ball incident. The flanker was red carded for his reaction while Matt Cox was merely sinbinned.
With over 20 minutes to go, this was going to be a major test of Gloucester's mental strength in what was now a hostile environment. It was a time for cool heads.
The initial response was first class as Sione Kalamafoni in particular stepped up to the plate with a series of powerful surges. A penalty followed and Billy Twelvetrees made it 11-3.
The game went into the final 10 minutes and started to open up a bit but a couple of raking touch finders from Billy Twelvetrees kept Gloucester in the right areas of the pitch.
Nerves started to jangle as Claverie slotted a 77th minute penalty to get Mont de Marsan back to within five points and the home crowd did their best to get their team back in it.
However, Gloucester held to clinch a bruising and bloody win on French soil.
Clinching the win was no mean feat when, despite being in the driving seat for so long, Gloucester really had to show some mettle to emerge triumphant.
Sione Kalamafoni was an ever willing, and powerful, ball carrier throughout the whole game and was deservedly named Man of the Match by Sky Sports.
However credit also has to go to a front row who belied their average age of 21 years and promise much for the future and to the experienced heads who steered Gloucester so skilfully through the troubled waters of the final 20 minutes.
The Amlin Challenge Cup is off and running and French opposiiton lie in wait again for Gloucester with Bordeaux-Begles the visitors to Kingsholm next Thursday.
|Mont de Marsan Score Card|
|Gloucester Rugby Score Card|