An excellent summary of the Persian Gulf expedition is given in The Sphere, May 15: The Shatt-el-Arab, (the united Euphrates and Tigris,) for the greater part of its course, forms the boundary between Persia and Turkey. Some twenty miles below Basra (or Bussorah) it is joined by the Kasun, near whose course, about a hundred miles from its mouth, are the Anglo-Persian Company's oil fields. The effective protection of these is necessarily an object of vital importance. It was also of considerable importance to create a diversion which should cause the Osmanli Generals to feel uneasiness as to a possible advance up the Euphrates. Whether more than the occupation of Basra and the protection of the oil fields was or is intended cannot, of course, be at present definitely stated. The expeditionary force, under Lieut. Gen. Sir Arthur Barrett, consisted--apparently--of three Indo-British infantry brigades, a brigade of Indian cavalry, and artillery and auxiliary services in proportion--in all probability some 15,000 to 18,000 men. It included at least three British battalions--the Second Dorsets, the Second Norfolks, and the Oxford and Bucks Light Infantry. The advanced brigade reached the Shatt-el-Arab on Nov. 7, and after a brief fight occupied Fao, a few miles up the river. On the 9th a night attack was made upon it by a force from Basra, which was easily beaten off. Shortly afterwards the main body of the expeditionary force began to arrive, and by the 16th it had entirely disembarked at Saniyeh, a place above Fao. The weather was wretched. Rain converted the alluvial flats into a wilderness of mud. The men were drenched and caked with the riverine clay, the very rifles were often choked. Meanwhile the advance guard carried out a reconnoissance up the river and located the enemy in position at Sahilo, about nine miles distant. They numbered about 5,000 men, with twelve guns, under General Subr Bey, the Vali (Governor) of Basra. The reconnoissance carried an advanced position with a loss of sixty killed and wounded, and withdrew unmolested to report. On the 17th General Barrett paraded for the attack the bulk of his force. After a trying march through a veritable quagmire, the troops sometimes up to their waists in slush, the division at about 9 A.M. came within range of the Turkish position, and the leading brigade, the Belgaum, (Major Gen. Fry,) deployed for attack.