We remember our war dead on Anzac Day, 25 April, the anniversary of the landings at Gallipoli in World War I. But our heaviest losses in that war occurred on the Western Front.

Our worst day was 12 October 1917 – the First Battle of Passchendaele. New Zealand lost 1000 soldiers in two hours because the high command ignored the effect of heavy rain on the battlefield.

The Ypres Salient, in Belgium, where the campaign took place was low lying. Prior to the war the water table was 35 centimetres below the surface. The weather that year had been poor and from July onwards was the wettest for 75 years. Millions of artillery shells fired over the previous three years had obliterated the canals and small creeks that drained the area, turning the ground into a quagmire. Some shell holes were so deep and the mud so viscous that men drowned in them when seeking shelter.

Eight days before Passchendaele, the New Zealand Division took part in the battle of Broodseinde. By this stage of the war, the British had evolved artillery tactics that delivered some success. The attacking soldiers walked forward 50 yards behind a creeping artillery barrage, giving the German soldiers little time to recover from the shelling before our troops were on top of them. Heavy artillery shells cut the barbed wire while those German pillboxes and artillery batteries that had been observed before the battle were specifically targeted.

The New Zealand division achieved all its goals, advancing 1900 yards through knee deep mud. This modest advance was deliberate so that the inevitable German counter attacks were well within the range of British artillery and easily halted. 

The New Zealand division suffered 25 per cent casualties, including 330 dead.

Intoxicated with such success, Field Marshall Douglas Haig, the general in overall command, was keen to push on as soon as possible. He was suffering from the delusion that the Germans were exhausted and a great breakthrough was imminent, through which his cavalry divisions would pour to end the war with one blow.

Before the attack could be renewed the artillery had to be moved forward over the captured ground. But the rain continued, making the ground all but impassable.

The mud was too deep to move the heavy guns up and many of the lighter guns bogged down. Shells for the guns were taken up by pack animal. One donkey, carrying two 18-pound shells slipped off the wooden duckboards and sank without trace into a flooded shell hole. Only a fraction of the necessary ammunition reached the guns. The mud and lack of time also prevented solid platforms being built for the guns that were in place.

Soldiers moving up during the night took four hours to struggle a mile through the mud, which was waist deep in places. Some never reached their start lines on time.

When the artillery barrage began it was so feeble that some soldiers could not distinguish it from the sporadic German shelling. Worse, when some of the British guns fired, the recoil shifted their alignments so that their next shells fell short and onto New Zealand troops.

The lack of heavy artillery left the 50-yard barbed wire entanglements uncut and the German’s concrete pillboxes undamaged. When the New Zealand soldiers went over the top they were slaughtered. Some companies suffered 85 per cent casualties and none of their objectives were reached. Stretcher-bearers struggling through the mire took hours to get wounded men to aid stations, sliding stretchers across the surface of the mud in places, while they struggled not to sink and drown.

Writing in Massacre at Passchendaele, New Zealand military historian Glyn Harper, believes the attack should never have been launched, blaming Haig and the generals below him for not listening to the junior officers who had warned of the terrible conditions beforehand. Other historians also blame Prime Minister Lloyd George and the War Cabinet who had allowed the Ypres campaign to proceed on the understanding that they would intervene to stop the fighting if it threatened to turn into a deadly debacle like the battle of the Somme the previous year. They failed to do so.

Ironically, over 500 years earlier, not far behind the frontline was the field of Agincourt, where heavy rain had given England one of its greatest military victories. A large French Army confronted Henry V on 25 October 1415. Most of Henry’s soldiers were archers. The French had six times as many men-at-arms and were confident of victory. However, they were badly led.

Their king, suffering temporary insanity, was absent. The French nobles, riven by bitter rivalries, all wanted to be in the front rank to capture the English king.

The field sloped uphill from the French positions and had been recently ploughed. Heavy rain overnight made footing treacherous – something the French leaders seemed to discount but Henry was aware of as his scouts had walked the field in the night.

After a three hour standoff, Henry took the initiative and advanced to within bowshot. On firm ground the French cavalry could have closed the gap in twenty seconds, making such an advance by lightly armed archers suicidal.  When they did charge, the cavalry was slowed by the mud. 

Their generation had not experienced massed English archery until that day. Shooting an arrow every five seconds, Henry’s 7000 archers could fire 80,000 arrows in a minute. The French cavalry was decimated. Those French soldiers protected by heavy plate armour sank knee-deep in mud churned up by the horses. Those who stumbled were trampled by those behind. A generation of French nobility died and Henry had one hand on the French crown.

If any good came out of Passchendaele, it was that the young officers who went on to become leaders in the Second World War had a stronger appreciation of the weather’s importance. The invasion of France, for example, scheduled for 5 June 1944, was put on hold for 24 hours because of a forecast of gales and rain. The forecast was correct, and catastrophe was averted.

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Referenced texts:

• Massacre at Passchendaele Glyn Harper
• Passchendaele: The Sacrificial Ground Nigel Steel and Peter Hart
• Passchendaele: The Untold Story Robin Prior and Trevor Wilson
• Agincourt Juliet Barker
• 1415 Henry V’s Year of Glory Ian Mortimer

This article was originally published in New Zealand Geographic March 2013. Stretcher-bearer image by John Warwick Brooke [Public domain], via Wikimedia Commons; artillery image courtesy of National Army Museum, New Zealand.

In Europe, the weather forecast for the invasion of France in 1944 played a crucial role in the success of the landings. Originally planned for the morning of June 5, the invasion was put on hold for 24 hours when bad weather was forecast. A window of acceptable conditions was then forecast for the morning of 6 June and the invasion went ahead. The German forecasters expected the bad weather to continue, so their armies in Normandy were off-guard when the landings began. Two New Zealand meteorologists were involved in the team making the correct forecasts, one Lawrence Hogben, was with the Royal Navy and the other Jim Austin was with the USAAF.

Rain fell from overcast skies and gale force winds drove large waves onto the beaches of Normandy as dawn broke on Monday 5 June 1944. To the Germans watching from their defences, there was nothing to show that this was the day the Allied Armies had planned to invade Europe. In fact, the operation had been put on hold because the bad weather had been forecast 24 hours before. Had it gone ahead in these conditions, the invasion would have been a catastrophic failure.

Nevertheless, the invasion had to occur on either the 5^th, 6^th, or 7^th of June to take advantage of the right conditions of moon and tide. Darkness was needed when the airborne troops went in, but moonlight once they were on the ground. And a spring low tide was necessary so that the landing craft could spot and avoid the thousands of mined obstacles on the beaches. If this narrow time slot was missed, the invasion would have to be delayed for two weeks.

The decision to postpone the invasion for 24 hours had been taken by Eisenhower and the Supreme Command at 0430 on Sunday 4 June. It was not taken lightly; so many ships were already at sea converging on the Normandy coast that the risk of detection was grave.

Nor had the forecast which prompted the postponement been easily arrived at. Eisenhower’s weather advice was provided by Group Captain Stagg, a forecaster seconded from the British Meteorological Office, who was in turn coordinating the advice of three forecasting teams: one from his own Meteorological Office, one from the Admiralty (which included an Aucklander, Lawrence Hogben - see photo) and one from the United States Army Air Forces (which included another New Zealander, Jim Austin, from Otago).

The advice of these groups was often diametrically opposed. The American team used an analogue method, comparing the current weather map with maps from the past, and were often over-optomistic. The Meteorological Office, aided by the brilliant Norwegian theoretician Sverre Petterssen, had a more dynamic approach using wind and temperature observations from high altitude provided by the RAF, and were closer to the mark.

The decision to invade on Tuesday 6 June, taken late on Sunday night and finally confirmed early Monday morning, was based on a forecast of a short period of improved weather caused by a strengthening ridge following the front that had brought Monday’s rain and strong winds. In the event, Monday’s bad weather had already given the Allies a crucial advantage; it had put the Germans off guard.

The Germans were uncertain exactly when and where the invasion would come, but believed the most likely place was Calais and that the most likely time was July. Hitler had long understood that the key to anticipating the timing of the invasion would be good weather forecasting.

But by the summer of 1944, German weather forecasters in France were hampered by a lack of weather observations over the Atlantic because their submarine fleet was now much depleted and the Luftwaffe had largely yielded the skies to the RAF. Consequently, their forecasters could not detect the subtle changes that would lead to a temporary improvement in the conditions starting Monday evening.

Rommel, the general commanding the German defence, had identified the period 5-7 June as high risk because of the state of the moon and tide. However, he also believed the Allies would not attempt an invasion without a guarantee of six days fine weather. Reassured by a Luftwaffe weather forecaster that the bad weather starting on 5 June would last at least three days, Rommel left France for Berlin.

There he hoped to persuade Hitler to relinquish his personal control of the panzer reserves in Holland to either himself or Von Rundstedt, who had overall command in the west. (As it transpired, Hitler held most of the reserves in the north, near Calais, for almost two months after the Normandy invasion because he was persuaded Normandy was only a diversion.)

Consequently, Rommel was in Germany when the invasion began and only made it back to the front at the end of the first day. The German navy also dropped their guard when the bad weather commenced, and did not patrol the Channel. Only five weeks before, some of their torpedo boats had crossed the Channel and attacked a night-time rehearsal for the landings. In 10 minutes, they sank two landing craft, crippled a third, and killed over 600 sailors and soldiers.

But on the Monday night when the invasion fleet of over 6000 ships crossed the Channel, the torpedo boats did not venture out until 4 a.m., and the fleet had already been anchored about 15 km off the beaches along a front of 100 km for more than an hour.

The weather on 6 June was tolerable but not ideal. Strong winds scattered the paratroops, some of whom overshot the Cotentin Peninsula and landed in the sea and were drowned. However, the Germans were also obliged to scatter their defences in response.

On the run in to Omaha beach, large waves swamped 27 out of 32 amphibious tanks, and all the artillery was lost. It was here that the Allies suffered their greatest losses of the day and briefly considered withdrawing. At the end of the first day, Allied casualties were 12,000 killed, wounded and missing, as against an estimated 75,000 if surprise had not been achieved.

The weather that northern summer was among the worst on record. Several days after the landings, a storm wrecked one of the artificial harbours that had been built and caused four times the losses in ships and equipment than had occurred during the landing. Two weeks later, in the second time slot suitable for the invasion, another major storm came through prompting Eisenhower to send Stagg a letter saying, “I thank the Gods of war we went when we did”.

Robert FitzRoy is famous as captain of the Beagle on the voyage when Darwin made his discoveries, although many New Zealanders also know FitzRoy as Governor of New Zealand before George Grey. But to meteorologists, FitzRoy is famous as one of the pioneers of weather forecasting; indeed, FitzRoy coined the term “weather forecasting”. He was also a superb navigator and surveyor whose charts of South America were still in use more than 100 years after he made them. 

FitzRoy’s career got off to a strong start at 14 when he topped his class at the Royal Naval College then, after four years at sea as a midshipman, he became the first candidate ever to pass the Lieutenant’s exam with perfect marks. 

Aged 23, he was given command of the Beagle, assisting Captain King surveying South America. Off the coast of Patagonia, a few months later, hurrying to a rendezvous, FitzRoy ignored the danger signs of a plunging barometer and threatening sky, with fatal consequences. A violent pampero wind caught the Beagle with too much sail and threw the vessel on her side. Topmasts and jib-boom were blown away, along with two sailors, who drowned. 

FitzRoy ordered both anchors dropped which righted the Beagle and pulled her head into the wind, saving her from foundering. Praised for his seamanship in saving the vessel, FitzRoy felt he could have done better in anticipating the sudden onset of the gale. 

The coastline of Tierra del Fuego and Magellan Straits proved so complex that the survey was broken off and the expedition returned to England. The following year, the navy hydrographer, Captain Beaufort (now known for the Beaufort Scale for measuring wind strength) persuaded the Lords of the Admiralty to resume the survey and FitzRoy was ordered back to South America. 

On this voyage, FitzRoy took Charles Darwin as a gentleman naturalist and companion. Constrained from conversing freely with officers under his command, FitzRoy needed someway to mitigate the loneliness of his position on such a long and stressful expedition. In fact, the previous commander of the Beagle had committed suicide after a breakdown. 

The voyage, lasting from 1831 to 1836, was hailed as a triumph and FitzRoy honoured with the Gold Medal of the Royal Geographical Society Medal. But the voyage eventually became famous for finding evidence for the theory of evolution, something that bitterly disappointed FitzRoy late in his life when Darwin’s Origin of the Species was finally published. By that time, FitzRoy’s religious views had hardened into a literal interpretation of the bible and he argued that large animals like dinosaurs had become extinct because the doors of Noah’s Ark were too small. 

In 1841, FitzRoy was elected to parliament then, two years later, offered the position of Governor of New Zealand. Backed with few troops and little money, the job was a poisoned chalice. 

FitzRoy arrived in time to adjudicate the Wairau massacre, finding that the New Zealand Company settlers had no right to try to arrest Te Rauparaha but that Te Rangihaeata was wrong to have executed the prisoners taken in the affray. This infuriated the settlers while Te Rauparaha sent a message that FitzRoy should not trouble to send soldiers to find him at Waikanae as he would be happy to turn up in Wellington with a thousand warriors on any date FitzRoy cared to name. In less than two years, political allies of the New Zealand Company engineered FitzRoy’s recall while the settlers in Nelson burnt him in effigy. 

FitzRoy’s voyage home was notable for a storm he forecast when the ship was anchored for the night in calm weather in Magellan Straits. Both FitzRoy’s barometers were falling fast but the captain ignored his warnings and retired below deck. Eventually, a young officer agreed to put out a heavy anchor on a heavy chain. When the storm struck at 2am, the heavy chain broke but tangled around the lighter chain. This was all that saved the ship from crashing into rocks and foundering with the loss of all onboard. 

The chance to develop his ideas on weather forecasting came to FitzRoy in 1854 when he was appointed Meteorological Statist to the Board of Trade. Initially tasked with compiling weather statistics for each part of the globe from ship’s logs, he took advantage of the invention of the telegraph to initiate forecasting. Barometers were distributed around the coast and their readings telegraphed to FitzRoy’s office every morning along with wind and temperature observations. Within hours a forecast would be telegraphed back. If FitzRoy thought a storm imminent, warning symbols of drums and cones were displayed from a mast. 

The storm warnings proved both successful and popular, although not infallible. FitzRoy also sent forecasts to the daily papers. Whereas his storm warnings were displayed as soon as the telegram arrived, the newspaper forecasts usually took 24 hours to appear and their success judged on how well FitzRoy’s more speculative outlook day turned out. 

In 1863, FitzRoy published The Weather Book containing his theories on how wind patterns and storms evolved as well as advice on how to use a barometer and a litany of horror stories of shipwrecks in storms.

FitzRoy was working 13 days a fortnight to improve his forecasts when criticism came to a head in parliament. FitzRoy had a nervous breakdown and took his own life on 30 April 1865. Born rich, FitzRoy died poor having expended much of his wealth advancing his work. A collection was taken up for the support of his widow and children. Notable among the contributors was Charles Darwin, who praised FitzRoy as ” an ardent friend to all under his sway.” 

The storm warnings issued by FitzRoy’s staff were discontinued but soon reinstated by public demand and remain his greatest legacy. Also testament to his abilities is the number of people who served under him on the Beagle who went on to distinguished careers. 

Today FitzRoy lives on in the name of one of the sea areas in the British marine forecasts, a mountain in Patagonia and numerous streets in New Zealand.

This article was originally published in New Zealand Geographic, issue 99 September-October 2009.