By no means. There is at least one earlier example (by about fifty years) plus probably others that I've overlooked.
In 1864, the North's Ulysees S. Grant decided to take direct advantage of the Union's numerical superiority of two to one, realizing that he could lose men in this proportion and still win. Viewed in this light, all but the most egregious of the North's previous "defeats" were actually Union victories (at Chancellorsville, for instance, the Confederates inflicted casualties in the ratio of only four to three and lost Stonewall Jackson). He combined this idea with a second one; that if the Confederate army could be separated from the defense of Richmond, the South would lose. Put another way, Grant could force the Confederates to fight on his terms by attacking Richmond and forcing Lee to defend it.
The Overland Campaign started with several near misses, and Union losses of nearly two to one. For all that, Grant sacrificed 60,000 men (against Confederate losses of about half that) in sixty days to get sixty miles closer to Richmond. When there was an outcry, Grant retorted "I plan to fight it out along this line if it takes all summer." With Grant closing in on Richmond, the Union loss rate went down to three to two, and ultimately, one to one. Lee simply could not survive such a war of attrition and finally fled Richmond to Appomattox, where he surrendered when caught by the Union army.