Western Front
Battle of the Somme: British capture trench northwest of Bazentin. German counter-attack held northwest of Pozieres.
Violent artillery fighting north and south of the Somme.
The ruins of St. Quentin Cathedral after it was hit by British artillery:
http://imgur.com/bMvrRZV © IWM (Q 87814)
Battle of Verdun: French Moroccan Colonial Regiment secure Fleury and Thiaumont (August 18) for good, repel German attacks (August 19 and 27-28).
Eastern Front
Brusilov Offensive: End of "Brusilov's Offensive" [Approximate date.] (see June 4th).
Russia announces a claim that they have taken 358,602 Germans and Austro-Hungarians prisoners during the Brusilov offensive.
Southern Front
Isonzo: At 1800 Cadorna suspends most successful Isonzo offensive yet after 3-4 mile gains on 15-mile front for 51,232 casualties (12,128 missing) vs estimated 49,035 Austrian (20,000 PoWs) and 30 guns.
Macedonia: Battle of Florina begins (see 19th): Pre-emptive Bulgar offensive into Greece (until August 28): 2 Bulgar columns attack Serb Danube Division near Florina and capture station, deploy 18,000 men (until August 19) to drive back Serb Third Army at West end of Allied line while Bulgar Second Army at east end begins advance to Struma.
Political, etc.
Germany: Meat ration fixed.
German and Bulgar notes to justify seizing Greek territory. {additional note: this highly implies that the German, Autro-Hungarian & Bulgarian incursions into Greece were otherwise unjustified, and illegal according to International law as it was understood in 1916. In reality, the Western Allies, France Especially, Russia & Serbia had long been unjustifiably & illegally (according to International Law as it was understood in 1916) occupying Greece & using it to launch attacks against the Central Powers.}
United Kingdom: Lloyd George: “Britain’s honor is not dead; her might is unbroken, her destiny unfulfilled, her ideals unshattered by her enemies.”
English writer Houston Stewart Chamberlain, a propagandist for Germany, becomes naturalized as a German citizen:
http://imgur.com/EeNlAIY
United States: JP Morgan Bank announces $250 million two-year loan to Russia.
Romania: Government formally agrees to join the Allies by entering the war by August 28; signs military convention at Bukharest.