An Act to establish and equalize the Grade of Line Officers of the United States Navy
Approved by President Abraham Lincoln on July 16, 1862, this Act officially established the Navy ranks of Rear Admiral, Commodore, Lieutenant Commander, and Ensign.
Law as Written 
Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That the active list of line officers of the United States navy shall be divided into nine grades, taking rank according to the date of their commissions in each grade, as follows, viz.:
SEC. 2. And be it further enacted, That the number of officers to each grade shall not exceed nine rear admirals, eighteen commodores, thirty-six captains, seventy-two commanders, one hundred and forty-four lieutenant commanders, one hundred and forty-four lieutenants, one hundred and forty-four masters, and one hundred and forty-four ensigns.
SEC. 3. And be it further enacted, That the vessels of the United States navy shall be divided into four classes, to be commanded, as near as may be, as follows;
First rates, by commodores.
Second rates, by captains.
Third rates, by commanders.
Fourth rates, by lieutenant commanders.
Lieutenant commanders may be assigned as first lieutenants of naval stations and of vessels not commanded by lieutenant commanders.
SEC. 4. And be it further enacted, That the Secretary of the Navy shall appoint an advisory board of not less than three officers, senior to those to be reported upon, who shall carefully scrutinize the active list of line officers above, and including the grade of masters in the line of promotion, and report to him in writing those who, in the opinion of the board, are worthy of further promotion in the following words: We hereby certify that _______ _______ has the moral, mental, physical, and professional qualifications to perform efficiently all his duties, both at sea and on shore, of the grade to which he is to be promoted, and recommend him for promotion.
SEC. 5. And be it further enacted, That the officers recommended shall be immediately commissioned, according to their present seniority, in the following grades and numbers, viz.: eighteen commodores, thirty-six captains, seventy-two commanders, one hundred and forty-four lieutenant commanders, one hundred and forty-four lieutenants, one hundred and forty-four masters, and one hundred and forty-four ensigns: Provided, That this number of officers remain upon the active list after the action of the board, otherwise so soon as the graduates from the Naval Academy are available for promotion.
SEC. 6. And be it further enacted, That a similar advisory board shall be appointed at least once in every four years: Provided, That the same officers shall not be eligible for two successive terms.
SEC. 7. And be it further enacted, That nine rear admirals may be appointed by the President, by and with the advice and consent of the Senate, who shall be selected, during war, from those officers upon the active list not below the grade of commanders, who have distinguished themselves, or shall hereafter most eminently distinguish themselves by courage, skill, and genius, in their profession: Provided, That no officer shall be promoted to this grade unless, upon recommendation of the President, by name, he has received the thanks of Congress for distinguished service. During times of peace vacancies to this grade shall be filled by regular promotion from the list of commodores, subject to examination as aforesaid.