Illustrations of history

Grenadiers were really common in the 18th and early 19th century, over a hundred years before the Boer war. They started appearing in the late 17th century even. They used tennisball-to-hockeyball-sized iron bombs with manually lit slow fuses. So their job was to walk forward, light fuses and fling 4 pounds of metal and powder towards the enemy. Repeatedly. While getting shot at. There's a reason the grenadiers were regarded as elite troops. France even had Horse Grenadiers at one point.

There's also a reason there were a lot less grenadiers when guns started getting better: standing in the open and lighting fuses is not the most survivable things to do when the enemy has rifles instead of muzzle-loading muskets. So yeah, grenades existed, but not until ww1 did they get popular again, as a secondary weapon instead of primary one.