The Union Jack is a flag consisting of the union of the national flag, and it is flown at the jackstaff in the bow of ships of war. Its size should be the same as that of the union of the flag with which it is flown. A pennant is triangular shaped, in some cases having a V-shaped notch cut in the outer end of the fly. The “commission pennant” is long and narrow, the portion next the hoist, or mast, having a blue field with thirteen white stars and the remainder being divided longitudinally into two parts, red and white. It is flown at the mainmast head of all ships in commission which have no officer on board above the rank of Captain in the Navy, and indicates that the ship carrying it is “in commission,” or on active service. On ships of war carrying an officer senior in rank to a Captain the prescribed distinctive flag for such officer is flown at the mainmast head in place of the commission pennant, and the ship is known as a “Flagship.” Naval officers above the rank of Captain in the Navy are called “Flag Officers.” These distinctive flags of higher command are shown in the illustrations. When two or more flag officers of the same grade are in the same fleet the senior one flies the blue flag of his grade and all the others fly the red flag of the grade. On any one ship of war only the distinctive flag of the senior officer of flag or higher rank is flown; thus, if the President is aboard an Admiral’s flagship the flag of the President is flown but not that of the Admiral. In former times the flag was carried into the front line of battle by the troops who used it as their rallying point, but in the battles of to-day, where every attempt is made to disguise and screen the lines of troops from the enemy, the flags and standards of the brigades and regiments would serve to mark the exact position of the lines and thus convey valuable information to the enemy and enable him to concentrate the fire of artillery and machine guns upon them. Therefore the flags are kept far in the rear to be carried in parades and ceremonies only or when the victorious troops march in triumph through the streets of cities captured from the enemy. In the accompanying illustrations the ensigns, flags and pennants of the principal maritime nations are shown, the national flag and the ensigns carried by the land troops being indicated in each case. In addition to the flags of the United States shown in the illustrations special flags are provided as distinguishing insignia for the Naval Reserve, the Naval Militia of the several States and territories, and for the merchant ships operated under the United States Shipping Board. [Illustration: BELGIUM ADMIRAL Vice Admiral 3 upper circles Rear Admiral 2 upper circles ENSIGN & MERCHANT FLAG COMMODORE] [Illustration: PENNANT] [Illustration: ITALY ENSIGN JACK MERCHANT] [Illustration: ADMIRAL VICE ADMIRAL REAR ADMIRAL] [Illustration: PENNANT] [Illustration: RUSSIA ENSIGN JACK MERCHANT FLAG]