Why did zimmermann make the offer to Mexico conditional on the US going to war against Germany?

Answer 1

Because it didn't help Germany otherwise.

Remember, Germany was fighting WW1. The Russians were finally quitting the war, and Germany finally would have been able to break the stalemate by throwing more troops at the Western Front.

But in order to achieve that, Germany needed to keep US troops out of the war. Having Mexico make war on the USA would have done that.

Answer 2

At the time, the United States had pledged to keep its neutrality during World War 1 (WW1). According to the telegram, in the event of the United States' entering the conflict against Germany, the German government was to provide Mexico with military and financial support to reconquer Arizona, New Mexico and Texas. The real reason was of course, to tie down American forces.

This demonstrated that Germany was actually provoking a war between Mexico and the United States, and public opinion demanded a response. The telegram thus became one of the reasons the United States entered WW1.

Answer 3

It offered the possibility of Germany to help Mexico recover New Mexico, Texas and Arizona.

Mexican president Venustiano Carranza knew the probability for Mexico to take over former territories was poor at best, due to the following reasons:

• Attempting to retake those territories would mean certain war with the US.
• No matter how generous the financial support from Germany would be, it would be worthless. Mexico could not use it to acquire arms, ammunition, or any other war supplies, as the United States was the only sizable arms manufacturer in the Americas. The British Royal Navy controlled the Atlantic sea lanes, so Germany could not possibly supply any quantity of arms.
• Even if Mexico had the military means to take back the lost territories it would have had severe difficulty accommodating and pacifying the large English-speaking population.
• Mexico had even cooperated with the ABC nations (Argentina, Brazil, Chile) to prevent a war with the United States during the Tampico Affair, generally improving relations. If Mexico were to enter war against USA it would strain relations with such countries.

Carranza formally declined Zimmermann's proposals on April 14, 1917, by which time the US had declared war on Germany.

Answer 4

It would have allowed Germany to wage war in Europe without American interference, as it would be entangled in a war against Mexico for at least 8-16 months.