Question: When was the helmet, that the M63 replaced, patented ?

Context paragraphs:
Modèle 1951 helmet: The Modèle 1951 helmet was a military helmet used by the French military (Army, Navy, Air Force and Gendarmerie), iconic of the Algerian War.  It replaced a variety of helmets used during the Second World War, including the Adrian helmet, Modèle 1945 helmet and American-supplied M1 Helmet.

Modèle 1978 helmet: The Modèle 1978 helmet is a modern military steel helmet used by the French Army under the "F1" designation and commonly called "heavy helmet" (other nicknames include "locomotive skin cap").  It replaced the Modèle 1951 helmet, and is superseded by the SPECTRA helmet.

M87 kevlar helmet: The M87 is a combat helmet of South African origin manufactured by South African Pith Helmet Industries (S.A.P.H.I) of Rosslyn.  The kevlar composite M87 replaced the steel M63 helmet during the late 1980s, and saw extensive use during the South African Border War, which took place from 1966 to 1989 in South-West Africa (Namibia) and Angola.  It is the current standard helmet of the South African National Defence Force.

Joseph-Martin Cabirol: Joseph-Martin Cabirol was a French man.  In 1855 he patented a new model of standard diving dress in Paris, mainly from Augustus Siebe's designs, and afterwards he made them.  The suit is made out of rubberized canvas.  The helmet, for the first time, includes a hand-controlled tap that the diver uses to evacuate his exhaled air.  The tap includes a safety valve which stops water from entering the helmet.  Until 1855 diving helmets were equipped with only three circular windows (front, left and right sides).  Cabirol's helmet introduced the later well known fourth window, in the upper front part of the helmet and letting the diver watch above him.  Having been presented to the "Exposition Universelle" in Paris Cabirol's diving dress won the silver medal.  This original diving dress and helmet are now preserved at the "Conservatoire National des Arts et Métiers" in Paris.

Lightweight Helmet: The Lightweight Helmet (LWH), also known as the Lightweight Marine Corps Helmet or Lightweight Marine Helmet, is an armored helmet that is used by the United States Marine Corps and U.S. Navy.  It is the U.S. Marine Corps' successor to the PASGT combat helmet, which it replaced.

Iraqi M80 helmet: The Iraqi M80 Helmet is a military helmet made of compressed canvas used by the Iraqi Armed Forces from the early 1980s onwards.  They were used in the Iran–Iraq War, The Persian Gulf War/Operation Desert Storm and the 2003 Invasion of Iraq/Operation Iraqi Freedom.  These helmets were originally manufactured and designed in South Korea but in 1990 an Iraqi-made version appeared, which is usually fitted with a distinctive rubber rim.  Both types of helmet are still in limited service with the Iraqi Security Forces but are being replaced by the American PASGT helmet.

M63 helmet: The M63 (nicknamed "Staaldak" in Afrikaans) is a combat helmet of South African origin.  Based on the French Modèle 1951 helmet, the M63 replaced the British type Brodie helmets during the early 1960s, and saw extensive use during the Rhodesian and Angolan bush wars.  It was issued until the 1980s when it was replaced by the M87 kevlar helmet.

SPECTRA helmet: The SPECTRA helmet or CGF Gallet Combat Helmet is the ballistic helmet in use as of 2016 in the French military, and the armies of several other countries.  Built by CGF Gallet (producer of the F1 helmet for firemen), it weighs 1.4 kg , is available in three sizes, and is made from ultra-high-molecular-weight polyethylene "Spectra" fibers, produced under license from Honeywell.  The SPECTRA helmet can stop shell fragments of 1.1 g travelling at 680 m/s , an 80% improvement over the Modèle 1978 helmet it replaced.

Brodie helmet: The Brodie helmet is a steel combat helmet designed and patented in London in 1915 by John Leopold Brodie.  In modified form it became the Helmet, steel, Mark I in Britain and the M1917 Helmet in the U.S. Colloquially, it was called the shrapnel helmet, Tommy helmet, tin hat, and in the United States the doughboy helmet.  Worn by Australians during WW2 and sometimes known as Panic Hat.  It was also known as the dishpan hat, tin pan hat, washbasin, battle bowler (when worn by officers), and Kelly helmet.  The US version, the M1917, was copied from the British Mk 1 steel helmet of 1916.  The German Army called it the "Salatschüssel" (salad bowl).  The term "Brodie" is often mis-used.  It is correctly applied only to the original 1915 "Brodie's Steel Helmet, War Office Pattern".

Mk 6 helmet: The Mk 6 helmet was the standard combat helmet of the British Armed Forces.  The Mk 6 replaced the Mk IV helmet (more correctly titled - Helmet Steel MK IV, General Service).  The jump in MK numbers is thought due to the confusion surrounding the MK IV helmet utilising the MK V lining, introduced in 1959.  The MK 6, introduced into service from 1985, is designed to accept modern ear protection, Bowman personal radios, and respirators.  The helmet is manufactured by NP Aerospace, and is reported to have an "almost unlimited service life" by the manufacturer.

Supporting paragraphs: M63 helmet Brodie helmet
Answer: 1915