The United States formally entered the First World War 100 years ago today. Some of the lessons from that devastating war still offer insights to leaders today.

#1 - Update Strategy with Technology – Machine guns represented a game-changing technology that made the war much deadlier. Strategies and tactics built in the days of calvary charges and muskets failed in the face of withering machine gun fire. Innovation in military equipment – e.g., the armored tank as a weapon against entrenched machine gun defenses – emerged during the war, but could have helped end the bloody stalemate earlier if developed before the war.

Lesson #1 – Monitor emerging technologies and regularly update your strategies and tactics.

#2 - Have a Plan B – The German generals had an attack plan – the Schlieffen Plan- to quickly take Paris to defeat the French and win the war. When the attack stalled before reaching Paris, both sides dug in and the war fell into three years of the horrific stalemate of trench warfare.

Lesson #2 – If you don't have contingency plans, you don’t have a plan.

#3 - Prepare an All Hands Response – During the Battle of the Marne early in the war, the French commanders enlisted help from Paris taxis to transport troops to the front. While the impact of a few thousand taxis was relatively small compared to the massive scale of a battle with over a million soldiers, it did boost French morale, at least as the legend grew over time. (Photo from Wikipedia by El monty CC BY-SA 3.0)

Lesson #3 – Anticipate people who would be helpful to enlist in a crisis so you can mobilize them quickly if needed.

#4 - Understand Your Entanglements – The assassination of the Austrian archduke quickly expanded into a global war because of the alliances between countries. Countries found themselves at war not because they had a conflict with each other, but because their friends of friends did.

Lesson #4 - Understand the dependencies your suppliers, sellers and other partners have because their problems can quickly become your problems.

#5 - Protect Against Hackers - The German government sent a proposal to Mexico to encourage them to wage war against the United States to regain lost territory. After the British intercepted and decoded the message, they shared it with the US Government. The resulting outrage in the US to this intercepted message - called the Zimmerman Note - was one of the final reasons (along with Germany's submarine attacks on US ships) that convinced the US to declare war against Germany.

Lesson #5 - Build strong defenses against getting hacked and have a response plan for when you eventually do.

Unfortunately, perhaps the biggest lesson from 'The War to End All Wars' was said best by the historians Will and Ariel Durant: "War is one of the constants of history ... and has not diminished with civilization or democracy."