Nearly quantum-defect-limited laser operation of a resonantly pumped ${\mathrm{Er}}^{3+}\text{:}{\mathrm{YVO}}_4$ at $1593.5\mathrm{nm}$ is demonstrated. Maximum slope efficiency of $\sim 85\%$ and true CW power of $\sim 13\mathrm{W}$ at $1593.5\mathrm{nm}$ were achieved with a beam propagation factor of $M_2\sim 1.05$ . This slope efficiency is, to the best of our knowledge, the highest efficiency ever reported for a crystalline Er-doped laser.