The following report is from recently declassified files, which even now are heavily redacted and all I can tell you is that this happened somewhen during WW2 near Menen in Belgium...
Reports had come in of strange goings on in a rural church somewhere between the battlelines and so one Lt. Smith found himself and his unit tasked to survey the site and gain intelligence on the German paranormal activities -
Later intelligence showed that this was not German activity although they did seek to gain knowledge of reanimation.The Menen Massacre
As the British forces approach the church through the woods they notice movement up ahead and pause to await orders from Lieutenant Smith...

Letting the enemy get closer so as to get a better idea of what they are facing Lt. Smith orders his men to hold fire as they hear the shuffling of the enemy through the trees...

...Blissfully unaware of their true nature and just how many of them there are ahead...

Meanwhile on the other side of the woods Leutnant Roth orders his men to maintain close formation, knowing that men have already been lost in the area to an unknown force.

Counting the approaching enemy and seeing numbers are on his side, Lt. Smith gives the order to engage in hand to hand and take them out silently...

Only to discover that it's not men they are facing but the walking dead! They quickly lay one back to rest...

And press on into the remaining two apparitions, only to realise that there are more of these foul creatures and the sound of combat is drawing them forward towards their position.

In contrast to the gung-ho approach of the British the Germans swiftly and stealthy sweep through the woods avoiding the notice of all but the birds...

...and one warped figure of a man...

Realising that they have been spotted the Germans decide the only way of silencing the sentry is too all rush him at once.

But the noise the combat makes begins to draw the attention of other mindless horrors.

The British seeing the danger of maintaining their position, against the approaching shambling horde team up to finish off the creatures already engaged finding that blows that would kill a man don't stop these things - The only way to be sure is destroy the head!

After crushing skulls with rifle butts, the British fall back towards the entrance of the church.

Praying that Lt Smith can get the door of the church open, before the incoming tide of undead flesh reaches them...

...but believing that the Lord helps those who help themselves, they give extra force to their prayers by backing it up with a hail of bullets.

Back in the woods the Germans bag their first abomination, which stood little chance against the combined force of five men.

Fortunately the church door is unlocked and the British hasten inside and bar the door behind them...

Just in time to stop the hellish mob from overwhelming them. The thudding on the doors only just louder than the pounding of thier own hearts.

The Germans seeing other shapes approaching through the woods, change direction...

...and find themselves in the middle of a large graveyard, where many of the graves show signs of having been disturbed.

Shaken by this, they are soon bolstered by the sight of loot - Besides one of the open graves they sight a chest full of strange paraphanelia and they head towards it to secure it.

As the undead begin to close in upon them.

The British now trapped within the church, decide to head for higher ground where they figure they can shoot down these mindless creatures at their leisure with their rifles.

Only to find their attention attracted by the sound of German gunfire, as Leutnant Roth and his men are emptying their weapons into the approaching undead.

Taking advantage of the German's distraction, the British riflemen calmly take aim at the Germans forcing their targets to take cover in the dirt.

Realising their path away from the creatures is into the path of British guns, the Germans hesitate for a cruicial moment and grasping arms claw at Lt Roth, pulling him towards mouths ripe with the fetid smell of death.

And it's not just the Germans, who have rotting arms welcoming them - The door of the church gave way under the press of flesh and the rearguard are forced to hold them off on the stairs leading up the tower

Not as brave (or perhaps as foolish?) as their Leutnant, Lt Roth's men fall back and leave him alone to face to oncoming horde.

With one of his men having the foresight to take the occult instruments with him as he takes cover round the corner of the church.

The brave Lt Roth, fights off the arms grasping towards him and smashes the head on one and forces the other creature back for a moment.

As up in the church tower the British fend of the lead zombie of the group now coming up the stairs, but seeing how many are behind him rapidly realise that there position is rapidly becoming untenable as they have allowed themselves to become trapped.

Knowing they can't go down the stairs, fueled by adrenaline they begin a rapid descent down the outside of the tower finding whatever handholds in the rough brick they can for purchase and only just in time as a group of the shambing undead reach the top of the tower.

Whilst the British might be making good an escape, the same could not be said for the Germans, all of whom had by now found themselves fighting for their lives against the undead in a swirling melee

A fight not all of them won as Lt Roth and one of his men fell victim to the teeth and claws of these vicious beasts, the smell of fresh blood seemed to whip them in to a frenzy as altogether they gave a bestial roar of...
BRRAAAIIIINNNNNSSSSSS!!!!!!!.......

Lying on the ground Lt Roth, knew it was over but instead of the blackness of death he expected, everything went red...

As his body despite it grievious wounds rose up and joined in the chant of brains, craving the flesh of his former allies as he to became one of the zombies...
To Be Continued....I apologise for ending it here for the moment, but it took longer than expected to get this much done tonight and I still have to pack for BLAM tonight, I should get the rest of this thrilling tale up tomorrow night though.