y between German East Africa and Portuguese East
Africa was formed by the River Rovuma, which, coming from the high
plateau and the mountains to the east of Nyasa, is one of the large
African rivers. Except in its highest reaches near Lake Nyasa it is not
fordable, and makes an admirable strategic line. However, as Portugal
came into the war after most of the German colony had already been
occupied by us, this river acquired strategic importance only toward the
end of the campaign, and then in a sense adverse to us, as General Van
Deventer has found to his cost. After the remnants of the German native
forces had been driven across the Rovuma at the beginning of December,
1917, our forces found the swift pursuit across the river a difficult
task. We are, however, now operating against the roving bands into which
the enemy force has split, and if ever they try to break back to their
occupied colony, they will find the line of the Rovuma a very serious
barrier.

[Sidenote: The search for the German raider _Koenigsberg_.]

[Sidenote: The _Koenigsberg's_ guns accompany the enemy on land.]

The eastern boundary of the colony is the coast-line of the Indian Ocean
for almost five hundred miles, with some very beautiful harbors, and it
was dominated by our navy from the day that war was declared. The Royal
Navy has played a very active part in our African campaigns, and one of
the most fascinating episodes of the war was the search for the
_Koenigsberg_, lost after she had destroyed the _Pegasus_ and done much
damage in the Indian Ocean. She was discovered in a most secluded branch
of the Rufiji River, and ultimately destroyed by seaplanes and monitors
in her impenetrable lair. Yet, though destroyed, she made her voice
heard over all that vast country, for her ten big naval guns, each
pulled by teams of four hundred stalwart natives, accompanied the enemy
armies in all directions, and, with other naval guns and howitzers
smuggled into the country, made the enemy in many a fight stronger in
heavy artillery than we were.

[Sidenote: Extensive enemy fortifications at the mountain gap.]

[Sidenote: The rainy season worse than imagined.]

From a strategic point of view, the northern frontier was the most
difficult of all. It passed north of Kilimanjaro, to the west of which
is a desert belt. East of this desert belt and Kilimanjaro the enemy
colony was protected by an almost impassable mountain system, with a
very narrow, swamp