I need stratagists!

So you need tactical advice, right?
First of first is it an alternative universe or is it historically accurate?

I am reminded of the line at the end of the movie “War Games,” where the computer, Joshua, says “Strange game. The only winning move is not to play.”

My background on this is as a history buff moreso than a strategist. I have a bachelor’s degree in history, and although I specialized in the American Civil War and World War II eras, I did take a class specifically on World War I. The problem with World War I trench warfare was that attacking was simply ineffective for nearly the entire war. Things only began to change in 1918. Although tanks played a role, the bigger factor was that both armies had lost so many men and so much equipment that it became more difficult to defend as effectively as they had earlier in the war when their armies were stronger. The United States’ entry into the war provided much-needed reinforcements for the allies and helped them to overwhelm the depleted German forces in the summer and fall of 1918. Germany’s economy also began to collapse.

I give this background because I’m not sure any attacking strategy could have been victorious at the Battle of the Somme in 1916, at least not by the standards expected in most other wars. It is important to note that the Somme is not seen as a terrible defeat in France so much as it is in Britain, where the high casualties horrified the country. What we do know about the Somme and can use with the hindsight of history is that the worst British casualties came at the north end of the line near Gommecourt. The British Fourth Army and French Sixth Army had more success in the middle and south end of the line. So let’s use that to our advantage and also flip the script a bit by taking advantage of the superior defensive technology of the day.

What we will do is attempt a feint on the northern end of the line by the British Third Army while the Fourth Army and French Sixth Army wait. Concentrate initial artillery on the northern end of the line. Send a small attacking force, but quickly withdraw and feign a retreat. We are going to bait the German Second Army into a counterattack. When the counter attack comes, we launch the attack by the Fourth Army and Sixth Army, while we let the Third Army hold the northern line, avoiding the catastrophic losses they suffered. We will press our initial success by swinging the attack by the Fourth and Sixth armies to the north, flanking the German Second Army. This should allow for the same or better territorial gains the Allies achieved without the high casualties that cause many to view it as a battle of attrition.

From what I remember the strategy for this battle was defend and attack, which obviously was a huge failure in both sides.
If Allied union wanted to win this without catastrophic casualties they needed to attack in 3 points, from which 2 should had been as initial attack and would drav German attention, after attention was drawn, simply send in the main force in a weaker point, hit a hole in German defensive line and simply crush them from 3 sides on the trench line, it is a very effective strategy and it was used in Winter battles here in Latvia... the result of this battle would be devastating to both sides alliance would have up to 60%casualties while Germans would have up to 80-90% the result of this battle would change a lot if it had gone this way.

For German side if they wanted to take alliance, they simply needed to withdraw them on open field with a small attacking unit, which would retreat after dealing a fast blow to enemy, well the unit would be sacrificed in the enemy's counterattack, but the waiting German machine guns, snipers and artillery would deal a fatal blow to enemy, before they could get anywhere near trench lines, meaning by half the way they would understand it is a trap and sound the withdraw and by that point comes in the cavalry, they simply has to take out majority of the runners, that would end in up to 70% casualties in alliance while Germans had used 90% from the small unit and few more men, it would be a major victory after which British and French forces would be devastated and most likely surrender changing the path of war a lot.

Note percentages are shown by the involved military units parts not all of the army together.
P.S. this is highly theoretical and it may haven't been possible historically, but we can never know all of the aspects of war, history hides them