If there was one event that you would have to choose that would single-handedly change the world as we know it, it would be the World Wars. World War I and World War II were collectively responsible for around 100 million deaths. Truly devastating times. There is no doubt that the WWs were a premier showcase of the absolute worst that we humans have to offer. That being said, The WWs were responsible for some of the best and most influential innovations. The necessity and drive that was created by fear and urgency led to countless technological breakthroughs. Even the computer your reading this from is a direct contribution due to WWII.

Wars require strong-arming. In the 20th century that was done using electrical contraptions and gadgets. One such necessity was communication. The commanders need to know where their armies are, be able to order their next move, form strategies, warn about attacks and much much more. All this can only be done effectively if you have a good mode of communication. Having better communication than your enemy will mean the difference in hundreds of lives. So armies get creative. Before the widespread use of radio communication, here are a few more rudimentary modes of communication:

Messenger Pigeons
Messenger Dogs
Semaphore
Signal Flags
Wig Wags
Semaphore with Flags

These methods have their obvious flaws. Almost all of them were mitigated by the advent of radio communication.

The use of Radio was first done during the wake of WWI. It was first used to communicate with ships using morse code. But quickly evolved to do much more. Before radio, armies used telephones with makeshift poles and lines running through the battlefield. These were, predictably, often cut and damaged from artillery fire. This forced them to adopt radio communication. This advancement was deemed to be invaluable to them. They were able to warn gas attacks beforehand, which gave the armies time to put on their gas masks. It helped give intricate details on bombing raids, attack battalions, etc. During World War I, radio communication was employed extensively by the navies of the world and had a major influence on the character of naval warfare. High-powered shore and ship stations made wireless communication over long distances possible.

The next step from the morse code was the invention of voice communication through radio signals. Like most inventions, this came due to a lack of a better alternative for aircraft communications. Morse code can get very confusing when combined with the rumble and noise of an aircraft engine. This led to many inaccurate messages being received. Moreover, a pilot had to send messages by tapping his keyer from his lap. This obviously led to many crashes.
But verbal communication required much higher frequencies than morse code. They also required much more power and the transceivers were big and bulky. These faults were quickly mitigated by the ingenious scientists and engineers drafted by most countries’ military. In 1916, The French Air Force successfully tested air to ground voice communication. The very next year they had air to air communication ready. Soon most countries joined the parade. Any army left lacking this vital technology was almost always doomed to begin with.
Another major innovation in radio technology as a result of necessity from the WWs was The Superheterodyne Receiver. This a new way to tune radios and to allow them to pick up distant signals. The receiver basically superimposed one radio wave on another and greatly amplified and filtered the resulting intermediate frequency, which was then demodulated to generate an audio signal, which was in turn amplified for output to loudspeakers or earphones.

All in all the World Wars led to much innovation and advancement in the field of wireless communication. That fact can never be understated. This led to TV broadcasts, radios being employed into cars, homes, buses and almost everywhere else. It also helped greatly improve the speeds and functionality of computers as external communication was more versatile. In conclusion, even though the wars were absolutely devastating, It led to many advancements that would benefit the world for centuries to come. There is always a silver lining.