Nearly 150 years before the advent of texts, tweets and e-mail, President Abraham Lincoln became the first “wired president” by embracing the original electronic messaging technology—the telegraph. The 16th president may be remembered for his soaring oratory that stirred the Union, but the nearly 1,000 bite-sized telegrams that he wrote during his presidency helped win the Civil War by projecting presidential power in unprecedented fashion.

The federal government had been slow to adopt the telegraph after Samuel Morse’s first successful test message in 1844. Prior to the Civil War, federal employees who had to send a telegram from the nation’s capital needed to wait in line with the rest of the public at the city’s central telegraph office. After the war’s outbreak, the newly created U.S. Military Telegraph Corps undertook the dangerous work of laying more than 15,000 miles of telegraph wire across battlefields that transmitted news nearly instantaneously from the front lines to a telegraph office that had been established inside the old library of the War Department building adjacent to the White House in March 1862.

Lincoln, who had a keen interest in technology and remains the only American president with a patent, spent more of his presidency in the War Department’s telegraph office than anywhere else outside of the White House, writes Tom Wheeler in Mr. Lincoln’s T-Mails: How Abraham Lincoln Used the Telegraph to Win the Civil War. As a president who craved knowledge, he trod a well-worn path across the executive mansion’s lawn to the War Department to monitor the latest intelligence arriving in dots and dashes.

David Homer Bates, one of the four original members of the U.S. Military Telegraph Corps, recounted in Lincoln in the Telegraph Room that several times a day, Lincoln sat down at a telegraph office desk near a window overlooking Pennsylvania Avenue and read through the fresh stack of incoming telegrams, which he called “lightning messages.” As telegraph keys chattered, he peered over the shoulders of the operators who scribbled down the incoming messages converted from Morse Code. He visited the office nearly every night before turning in and slept there on a cot during pivotal battles.

According to Wheeler, Lincoln sent barely more than one telegram a month in the first year of his presidency, but that changed as he grew increasingly frustrated with the war’s plodding progress. He wielded the nascent technology to take greater control of the war effort after sending a flurry of telegrams on May 24, 1862, that directed his generals to move at once against the forces of Confederate General Thomas “Stonewall” Jackson.

The telegraph allowed the president to act as a true commander-in-chief by issuing commands to his generals and directing the movement of forces in nearly real time. For the first time, a national leader could have virtual battlefront conversations with his military officers. The paucity of interstate telegraph lines in the South precluded Confederate President Jefferson Davis from doing the same.

Lincoln wasn’t shy about stepping in and asserting his thoughts on telegrams that weren’t even addressed to him. “The telegraph was both his Big Ear, to eavesdrop on what was going on in the field, and his Long Arm for projecting his leadership now informed by the newly garnered information,” Wheeler writes. When General Ulysses S. Grant rejected General Henry Halleck’s suggestion to remove troops from the siege of Petersburg in 1864, the president lent this support after reading their communications: “Hold on with a bull-dog grip, and chew and choke as much as possible.”

To Lincoln, the telegraph office was not just a 19th-century command center, but a sanctuary from the throngs who descended upon the White House every day in search of jobs and favors. “I come here to escape my persecutors,” Lincoln quipped to telegraph operator Albert B. Chandler. Telling homespun tales and cracking jokes, the president befriended the office’s telegraph operators. “He would there relax from the strain and care ever present at the White House, and while waiting for fresh dispatches, or while they were being deciphered, would make running comments, or tell his inimitable stories,” Bates wrote. When news of Grant’s capture of Vicksburg, Mississippi, arrived by wire in 1863, Lincoln flouted regulations and bought beer for the operators, drinking a sudsy toast with the general’s telegram in his hand.

On April 8, 1865, Lincoln himself telegraphed the office from City Point, Virginia, with news of Grant’s capture of Richmond. A week later, the telegraph office broke the devastating news of Lincoln’s assassination to the nation as it tapped out the message that Secretary of War Edwin Stanton wrote from the president’s deathbed across the street from Ford’s Theatre: “Abraham Lincoln died this morning at 22 minutes after Seven.”